POPULATION COMPOSITION AND AGEING

The age structure of Australia's population has changed significantly over the last century. A decline in fertility rates, and increases in life expectancy have seen the median age rise from 22.5 years in 1901 to 36.9 years in 2009. Children under 15 years made up 19% of the population in 2009, compared with 35% in 1901. Conversely, in 1901 60% of the population were aged 15-64 years (often referred to as the 'working age' population), but this proportion had increased to 68% by 2009. The proportion of the population in older age groups also increased, from 4% in 1901 to 13% in 2009 for those aged 65 years or over, and a similar pattern was seen for those aged 85 years or over - rising from 0.1% in 1901 to 1.7% in 2009 (or from 4,200 to 379,400 people aged 85 years or over). As a consequence, the dependency ratio, has decreased from 64 to 48 people outside the 'working age' for every 100 inside it.

The balance between men and women has also changed. In 1901 there were 110 males for every 100 females (in part due to the relatively high proportion of Australian immigrants who were male) (ABS 2008a). This gap has closed. In 2009, there were slightly fewer males than females in Australia (99.2 males for every 100 women). However, this sex ratio did differ by age. In 2009, the sex ratio at birth was approximately 105 males per 100 females. Higher male mortality rates resulted in the ratio being about even for the 30-64 years age group (98.8 males per 100 females) and decreasing markedly above the age of 65 years (83.8 males per 100 females) (ABS 2009b). Net overseas migration can also influence the sex ratio, especially in the younger working ages where there is often a greater proportion of male migrants.

For a more detailed view of the changing age and sex structure of the Australian population try out the ABS animated population pyramids.