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Feature Article - Western Australia's Age and Sex Distribution
PROPORTION OF POPULATION - Age Groups, Western Australia
The most noticeable change to the age distribution of Western Australia between 1991 and 2001 was the increasing proportion of the population aged 45 to 54. This age group represents the 'baby boomer' generation - those born in the years following World War Two. During this period, the number of babies born increased greatly in comparison with the preceding 'baby slump' of World War Two and the depression years (Hugo, 2001). As this cohort continues to age they are likely to have a significant effect upon the composition of society and the level and nature of economic activity, including the supply of, and demand for, services such as health care.
While the age and sex distribution of Western Australia has generally reflected the age and sex distribution of Australia, the regions of Western Australia have continued to show their own distinctive distributions.
The ABS uses the Australian Standard Geographic Classification (ASGC) as its standard geography for disseminating statistical data. The ASGC aggregates up from Census Collection Districts, to Statistical Local Areas, to Statistical Subdivisions, to Statistical Divisions, to the State/Territory and finally the national level. The analysis in this article focuses upon the Statistical Division (SD) and the Statistical Local Area (SLA) levels. In Western Australia, most SLAs are equivalent to Local Government Areas. For more information refer to Statistical Geography: Volume 1 - Australian Standard Geographic Classification (ASGC) (ABS Cat. No. 1216.0), available on the ABS website.
For statistical purposes, Western Australia is divided into nine SDs. Each SD has a distinctive population profile, ranging from the large urban centre of Perth to the sparsely populated Kimberley SD, as shown in the following tables.
POPULATION AND SEX RATIO BY STATISTICAL DIVISION
MEDIAN AGE (YEARS) BY STATISTICAL DIVISION
As the following diagram shows, the age distribution across the State also varies from the 'youthful' North to the 'old' South, with further variation within the SLAs that make up each SD.
MEDIAN AGE OF ALL PERSONS BY STATISTICAL DIVISION
The analysis that follows discusses each SD and the key trends in their component SLAs.
Comprising the metropolitan area, the Perth SD is the capital of Western Australia and the State's major urban area. Between 1991 and 2001, the Perth SD grew from 72.7% to 73.3% of the State's total population. Western Australia has the highest proportion of total State population living in its capital of any State except for South Australia. Given the Perth SDs large share of the State population, it is therefore not surprising that the population distribution of this SD closely resembles that of the State as a whole.
Over the 10 years to 2001, the Perth SD grew at 1.6% per annum to 1,397,000 persons, faster than the State as a whole (1.5%).
From 1991 to 2001, the median age of all persons in the Perth SD increased from 32.0 to 35.0 years. This compares with a change from 31.5 to 34.8 years for the State as a whole over the same period of time.
Perth was the only SD in Western Australia where females outnumbered males, with a sex ratio of 97.9 in 2001. The sex ratio for the remainder of the State was 106.9. The ratio of males to females varies in different age groups; in the Perth SD there were more males than females aged 0 to 14 and more females than males aged 65 years and over. There were almost equal numbers of males and females in the traditional working age population (15 to 64 year olds). This pattern has changed little since 1991. The greater number of females in older age groups can be attributed to the greater life expectancy of females compared with males.
PROPORTION OF POPULATION - Age Groups, Perth SD, 1991 and 2001
The most apparent change to the age distribution of the Perth SD between 1991 and 2001 was the decreased proportion of the population in age groups less than 45 years, and the increased proportion of the population 45 to 49 years and older. Although every five year age group increased in population over this period, the proportion of persons under 45 years of age decreased from 70.9% to 65.4% of the total population. Conversely, the proportion of the persons aged 45 and older increased from 29.1% to 34.6% of the total population. As with Western Australia as a whole, this effect was driven by the 'baby boomer' population, with the largest increases in relative size seen in the population of persons aged 45 to 54 years.
STATISTICAL LOCAL AREAS
The Perth SD has 37 SLAs ranging in size from Perth-Inner (790 persons) to Joondalup-South (108,300 persons). The Perth SD's highest and lowest sex ratios were seen in the SLAs with the smallest populations. For example, Perth-Inner had a sex ratio of 201.5, while Fremantle-Inner had a population of 820 persons and a sex ratio of 156.4. The SLAs with the lowest sex ratios, Peppermint Grove (74.4) and Mosman Park (87.8) also had low population figures.
The SLAs with the lowest median ages in the Perth SD (Wanneroo-North-West, Wanneroo-South, Swan, Kwinana, Gosnells and Joondalup-North ) were all located on the rapidly growing urban fringe of the Perth SD. Between them, these SLAs accounted for over 20.0% of Perth's population and almost half of the growth in Perth's population between 1991 and 2001. Each of these SLAs had a median age of 32.5 years or less, a low proportion of older persons and a high proportion of children, all characteristics of areas with a high concentration of young families. The population growth in these areas is associated with young families seeking affordable housing.
In contrast, the areas with the oldest median ages were well established, and either barely growing or in decline. Claremont, Fremantle - Inner, Fremantle - Remainder, Cottesloe, and Nedlands had median ages between 38.9 and 40.5 years, a low proportion of children and a high proportion of older persons.
SOUTH WEST SD
The South West was the second most populous SD in Western Australia, comprising 10.2% of the State's population. The South West includes the urban areas of Bunbury and Mandurah, as well as rural shires such as Manjimup, and contains a diverse range of industries, including tourism, forestry and agriculture.
Between 1991 and 2001, the South West grew by 49,200 persons to 194,900 persons at an annual average rate of 3.0% (the second fastest rate of increase of any Western Australian SD over that period).
The median age in the South West SD was higher and increasing faster than that in the Perth SD. Between 1991 and 2001 the median age of all persons in the South West increased from 32.7 to 36.9 years. This compares with an increase from 32.0 to 35.0 years for all persons in the Perth SD.
In 2001, the South West SD had a sex ratio of 101.3, down from 103.8 in 1991.
PROPORTION OF POPULATION - Age Groups, South West SD, 1991 and 2001
The most apparent feature of the age-sex distribution of the South West SD compared with the Perth SD was the small proportion of the population made up by persons aged 20 to 29. In 2001, this age group made up 11.1% of the South West's population, compared with 14.6% of the Perth SD's population. As in the Perth SD, the high proportion of 'baby boomers' was also apparent.
STATISTICAL LOCAL AREAS
The South West SD experienced strong growth between 1991 and 2001. Growth in the area was dominated by the Mandurah and Murray and the Bunbury regions, which showed distinctive population distributions. Growth in Mandurah and Murray is associated with older persons moving to the area for lifestyle reasons. These SLAs accounted for more than 40.0% of the growth in the SD over that period and bucked the trend of rapidly growing SLAs having younger populations, with median ages of 40.0 and 41.1 years respectively. Murray was the SLA with the State's second oldest median age.
Growth in and around Bunbury was also strong. Bunbury and it's urban fringe accounted for a quarter of the SD's growth between 1991 and 2001. The median age of all persons in Bunbury (34.9 years) was less than the SD average (36.9 years), while the SLAs on the urban fringe of Bunbury (Capel-Part A, Dardanup-Part A and Harvey-Part A) had even lower median ages (30.9 to 33.9 years).
LOWER GREAT SOUTHERN SD
The economy of the Lower Great Southern SD is associated with a range of industries, including agriculture and tourism. This SD had a population significantly older than the Perth SD and it's population growth was comparatively slower.
From 1991 to 2001, the Lower Great Southern SD grew by an average of 0.9% per annum, to 53,400 persons.
In 2001, the Lower Great Southern SD had a median age of 36.2 years for males and 37.7 years for females, compared with 32.2 and 32.7 years in 1991. The Lower Great Southern had the oldest median age for females of any Western Australian SD in 2001.
As with Western Australia as a whole, the sex ratio for the Lower Great Southern SD decreased between 1991 and 2001, from 103.7 to 102.6.
PROPORTION OF POPULATION - Age Groups, Lower Great Southern SD, 1991 and 2001
As in the South West SD, the most apparent feature in the age-sex distribution of the Lower Great Southern SD was the small, and decreasing proportion of persons aged 20 to 29.
STATISTICAL LOCAL AREAS
A distinction can be drawn between those SLAs in the Lower Great Southern SD which did and did not grow between 1991 and 2001. Only four of the 13 SLAs in the Lower Great Southern grew between 1991 and 2001; Albany-Central, Albany-Balance, Denmark, and Plantagenet. These were the four largest SLAs in the Lower Great Southern and accounted for over three quarters of the population. They also had sex ratios close to the SD average (102.6) and, with the exception of Albany-Balance, all had populations with median ages greater than that of the SD as a whole (36.9 years).
UPPER GREAT SOUTHERN SD
The wheatbelt region of the Upper Great Southern was the least populous SD in WA with 18,700 persons, contributing only 1.0% of the State's total population. The region is known principally for agricultural activity.
The Upper Great Southern was one of only two declining SDs in Western Australia, with 2,500 less persons in 2001 than in 1991, an annual average decrease of 1.2%.
The median age of the Upper Great Southern increased the most of any SD between 1991 and 2001, from 30.7 to 36.4 years for males, and from 31.0 to 36.6 years for females. This made the Upper Great Southern the second oldest SD in Western Australia, with the oldest median age for males of any SD in the State.
In 2001, the Upper Great Southern SD had a sex ratio of 106.5, down from 109.7 in 1991. Males consistently outnumbered females in all age groups under 75 years.
PROPORTION OF POPULATION - Age Groups, Upper Great Southern SD, 1991 and 2001
The most notable change to the age distribution of the Upper Great Southern SD between 1991 and 2001 was the declining numbers of persons aged under 45 years - there were 3,600 less persons in this age group in 2001 than in 1991. Conversely, there were 1,200 more persons aged 45 years and older in 2001 than in 1991.
STATISTICAL LOCAL AREAS
Every SLA in the Upper Great Southern SD decreased in size from 1991 to 2001. The SLA of Narrogin (Town) was the largest single SLA in the Upper Great Southern and accounted for over 25.0% of the SD's population. This SLA stood out for it's low median age (32.3 years) and low sex ratio (94.1). All other SLAs in this SD had comparatively high sex ratios (with two thirds of SLAs having sex ratios of greater than 110.0) and median ages (from 35.1 to 39.4 years). The surrounding Narrogin Shire had the SD's highest sex ratio (121.8) and a median age of 37.8 years.
The Midlands SD extends from Chittering and Toodyay, near the urban fringe of Perth, to the inland wheatbelt SLA of Mukinbudin.
The Midlands grew by 2,600 persons between 1991 and 2001, to 53,700 persons, and had an annual average increase of 0.5%. Of all SDs in Western Australia experiencing positive growth between 1991 and 2001, the Midlands SD increased by the least number of people.
At 37.1 years, the Midlands had the oldest median age for all persons of any SD in Western Australia - up from 31.5 years in 1991. With the exception of the Upper Great Southern SD, this SD also had the largest increase in the median age of persons between 1991 and 2001.
In 2001, this SD had a sex ratio of 109.0 compared with 110.3 in 1991, with slightly more males than females in almost every age group under 75 years of age.
PROPORTION OF POPULATION - Age Groups, Midlands SD, 1991 and 2001
The most notable change to the age distribution of the Midlands SD between 1991 and 2001 was the decreasing proportion of the population aged under 35 years and the increasing proportion made up by persons aged 40 and over. A similar pattern was observed for the total State population and the Perth SD, and can be partially attributed to the ageing of the 'baby boomer' population.
STATISTICAL LOCAL AREAS
Growth in the Midlands SD was confined to eight of the region's 29 SLAs. These SLAs (Toodyay, Gingin, Chittering, York, Dandaragan, Dalwallinu, Beverley and the Shire of Northam) accounted for over 45.0% of the SD's population in 2001, and grew by a total of 5,800 persons between 1991 and 2001. The two SLAs which grew the most (Toodyay and Gingin) increased by a combined total of 2,800 persons, more than the total growth of the SD for that period of time. The SLAs which grew tended to have older median ages than those which decreased in size - four of the eight SLAs which recorded growth had median ages of over 40 years, with only one SLA (Dalwallinu) having a median age (32.8 years) less than the median age of the SD as a whole (37.1 years). Beverley had the highest median age of any SLA in Western Australia (43.3 years).
The SLAs in the Midlands SD which declined in numbers between 1991 and 2001 were generally smaller and further from Perth than those which grew. An exception to this trend was the Town of Northam - the largest SLA in the SD, and as close to Perth as most of the SLAs which grew. Between 1991 and 2001 the population of the Town of Northam decreased by 520 persons.
SOUTH EASTERN SD
The South Eastern SD extends from the coastal SLAs of Ravensthorpe and Esperance and the mining centre of Kalgoorlie/Boulder, to the remote inland Ngaanyatjarraku. The mining industry is crucial to the economy of this SD.
Between 1991 and 2001, the South Eastern SD increased by 2,600 to 55,300 persons, an average increase of 0.5% per annum.
The age-sex distribution of the South Eastern SD reflects the relatively large proportion of the population made up by Indigenous persons and by persons employed in the mining industry. Low median ages are characteristic of the high fertility and mortality rates associated with the Indigenous population. A high sex ratio, a high proportion of the population in the working age group (15-64 years) and a low proportion aged 65 and older are characteristic of an area with a high proportion of the population employed in mining.
PROPORTION OF POPULATION - Age Groups, South Eastern SD, 1991 and 2001
In 2001, the South Eastern SD had Western Australia's third youngest population, with a median age for all persons of 31.0 years, compared with 27.8 in 1991.
The sex ratio for the South Eastern SD was 119.5 in 1991, decreasing to 114.5 in 2001. Males outnumbered females in every age group under 75 years.
STATISTICAL LOCAL AREAS
Although the SLAs which made up the South Eastern SD generally had low median ages and high sex ratios, there was considerable variation between the SLAs in this SD. For example, the Shire of Ngaanyatjarraku had a very low median age (the State's second lowest, 26.2 years) and a sex ratio of 98.2. The population of Ngaanyatjarraku was almost entirely Indigenous. Only one SLA in the SD (Ravensthorpe) had a median age (36.8 years) greater than the State average (34.8 years). The SLAs with the highest sex ratios in the SD, such as Laverton (192.5), were dominated by the mining industry.
The SLAs of Kalgoorlie/Boulder-Part A and Esperance accounted for over three quarters of the population of the SD. Of the two shires, Esperance had an older median age (34.4 years), and a more even sex ratio (104.3) than Kalgoorlie/Boulder-Part A (median age 29.9 years and sex ratio of 113.0).
The South Eastern SD had a very small population of persons aged 65 years and over. The SLA with the highest proportion was Esperance (9.9%), whereas Coolgardie had the lowest proportion (2.5%).
The SLAs which made up the Central SD varied from the urban and coastal Geraldton and the remote and inland Wiluna to the wheatbelt Shires of Carnamah and Perenjori. The region includes a range of industries, including pastoral activity, agriculture, mining and fishing.
The Central SD grew by 2,800 persons in the ten years to 2001, to 60,700 persons, representing an annual average growth rate of 0.5%. Of all the Western Australian SDs which increased in size between 1991 and 2001, the Central SD had the slowest rate of increase as a percentage of the population, marginally behind the Midlands and South Eastern SD's.
In 2001, there were 108.2 males for every 100 females, down from 112.5 in 1991. There were more males than females in every five year age group under 80 years.
PROPORTION OF POPULATION - Age Groups, Central SD, 1991 and 2001
The median age of the Central SD increased over this period of time, with the median age for all persons increasing from 29.4 to 34.0 years.
STATISTICAL LOCAL AREAS
There are 22 SLAs in the Central SD, with most of the growth between 1991 and 2001 occurring in the coastal SLAs nearest to Geraldton (Greenough-Part A, Greenough-Part B, Irwin, Chapman Valley and Northampton). Over this period, these SLAs grew by 5,900 persons, more than double the total growth recorded by the SD. By far the greatest growth (3,800 persons) was in the portion of Greenough Shire on the urban fringe of Geraldton (Greenough-Part A). The median age for Greenough-Part A was lower than in Geraldton (31.9 compared with 34.1 years respectively). In contrast, the rural SLAs surrounding Geraldton which grew were older (median ages 36.9 to 39.3 years) than Geraldton. Geraldton was the only SLA in the SD with a sex ratio of less than 100.0 (97.5). Despite growth in the surrounding SLAs, the City of Geraldton itself decreased in size (by 1,000 persons) over this period.
While growth around Geraldton was strong, virtually all other SLAs decreased in population size between 1991 and 2001. The only other SLAs in the SD which grew between 1991 and 2001 were Wiluna, Shark Bay, Upper Gascoyne, and Murchison. These SLAs grew by a total of 780 persons.
The State's highest sex ratios were evident in this SD, in the SLAs of Yalgoo (244.8) and Wiluna (208.7), reflecting the influence of the traditionally male-dominated mining industry. Median ages varied across the SD, from Murchison (26.8 years) to Sandstone (40.0 years). These are also the State's least populous SLAs, with populations of 160 and 140 persons respectively.
The Pilbara SD is made up of four SLAs - Ashburton, East Pilbara, Port Hedland and Roebourne. The region is characterised by the relatively large proportion of the population which is Indigenous. The economy of the Pilbara is closely linked to the mining industry, and changes in the population of the region reflect the changing fortunes of this industry.
From 1991 to 2001, the Pilbara decreased by 6,900 persons to 39,700 persons, the largest decrease of any SD. This equated to an annual average decrease of 1.6%, the fastest rate of decrease of any SD in Western Australia.
The age-sex distribution of the Pilbara SD reflects the impact of the mining industry and the large proportion of the population which is Indigenous. The Pilbara has a distinctive age-sex population distribution, with very few persons aged over 65, relatively few 15 to 24 year olds, and a working age (15 to 64 years) population dominated by males.
PROPORTION OF POPULATION - Age Groups, Pilbara SD, 1991 and 2001
The Pilbara had the highest sex ratio of all SDs (121.4). Unlike all other SDs, there was almost no change in sex ratio in the last ten years. There were more males than females in every age group under 80 years, with this feature most pronounced between the ages of 30 and 59.
The Pilbara had the second youngest median age for all persons of any SD, with a median age of 30.7 years for males and 28.8 years for females, up from 28.6 and 25.9 years respectively in 1991. The increase in median age for all persons from 1991 to 2001 (2.4 years) was the least increase of any SD in Western Australia over that period - this compares with an increase of 3.0 years for the Perth SD and is less than half the increase experienced by the Upper Great Southern (5.7 years). The higher median age for males than females was influenced by the greater number of males than females in the older working ages.
STATISTICAL LOCAL AREAS
Of the four SLAs which made up the Pilbara, only Port Hedland grew in the 10 years to 2001, increasing by 160 persons. East Pilbara, Ashburton and Roebourne decreased in size, by 4,200, 1,900, and 860 persons respectively. Despite population change in different directions, the four SLAs shared consistent age-sex profiles; all had low median ages (ranging from 29.5 to 30.2 years of age), high sex ratios (118.9 to 128.6), and a large proportion of the population aged 15 to 64 (69.7% to 71.0%).
The SLAs which made up the Pilbara had the State's lowest proportions of persons aged 65 years and over, ranging between 1.6% of the total population of Ashburton to 2.4% of the population of Port Hedland. In comparison, 11.2% of Perth's population was aged 65 years and older.
The Kimberley SD consists of four SLAs - Broome, Derby-West Kimberley, Halls Creek, and Wyndham-East Kimberley. The economy of the region is based on tourism, pastoralism, agriculture and mining.
Between 1991 and 2001, this SD grew by an average rate of 3.4% per annum, the fastest rate of any SD; this is more than double the rate of growth shown by the Perth SD over the same period of time (1.6% per annum). This SD was the second least populous in Western Australia in 2001, with a population of 32,700 persons.
The age distribution of the Kimberley reflects the relatively large proportion of the population made up by Indigenous persons. The high fertility and mortality rates associated with the Indigenous population are factors which led to the lowest median age for all persons of any SD in Western Australia. In 2001, the Kimberley SD had a median age of 28.1 years for all persons, up from a median age of 25.6 years in 1991. This compares with a median age for all persons of 35.0 years for the Perth SD in 2001. With the exception of the Pilbara SD, the Kimberley had the least increase in median age of any SD in Western Australia between 1991 and 2001.
PROPORTION OF POPULATION - Age Groups, Kimberley SD, 1991 and 2001
As in the Pilbara, a notable feature of the Kimberley SD age distribution was the small proportion of persons aged 65 and over. In 2001, persons in this age group made up 4.0% of the SDs population. This compared with 11.2% of the population of the Perth SD in this age group.
From 1991 to 2001, the Kimberley SD continued to have a high sex ratio, despite decreasing from 115.9 to 114.7. In 2001, there were more males than females in every 5 year age group under 80 years of age.
STATISTICAL LOCAL AREAS
All four SLAs in the Kimberley SD had high sex ratios (110.6 to 122.0) and low median ages compared with the State average. Despite this, there were differences between the SLAs, with Halls Creek having the State's lowest median age (23.1 years), and Derby-West Kimberley the State's third lowest (26.6 years). While still young compared with the State median age (34.8 years), the SLAs of Wyndham-East Kimberley and Broome were older, at 29.1 and 29.6 years respectively. The SLA of Broome had the highest median age of the SD, and accounted for over 40.0% of the SD's population, and over half of the growth in the SD's population between 1991 and 2001. Growth in the Broome SLA is at least partially associated with the strong tourism industry and the attractive lifestyle offered by the region.
A Century of Population Change in Western Australia, Feature Article, in Western Australian Statistical Indicators, September 2001 (ABS Cat. No. 1367.5)
Berger, M., 2000, Rebasing Australia's Demographic estimates Using the 2001 Census of Population and Housing, ABS Demography Working Paper 2001/6
Demographic Estimates and Projections: Concepts, Sources, and Methods (ABS Cat. no. 3228.0)
Hugo, G., 2001, A century of population change in Australia, Centenary Article, in 2001 Yearbook Australia, pp. 169-210 (ABS Cat. No. 1301.0)
Population by Age and Sex, Western Australia, June 1991 and June 1996 (ABS Cat. no. 3235.5.55.001)
Population by Age and Sex, Western Australia, June 2001 (ABS Cat. no. 3235.5.55.001)
Regional Population Growth, Australia and New Zealand, 1991 to 2001(ABS Cat. No. 3218.0)
Statistical Geography: Volume 1 - Australian Standard Geographical Classification (ASGC) (ABS Cat. No. 1216.0)
Understanding Population Measures, Feature Article, in Western Australian Statistical Indicators, June 2002 (ABS Cat. No. 1367.5)
PRINTER FRIENDLY VERSION OF "WESTERN AUSTRALIA'S AGE-SEX DISTRIBUTION"
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