Like Darwin, Canberra had a high rate of natural increase. However it also had a sizeable gain through net migration, giving it the third highest level of growth for capital cities over the period 1986-94. Perth also had a high rate of net migration and consequently the second highest overall growth rate. Age structure Capital cities differ slightly in the median ages of their populations. There is a dynamic relationship between the median age of a city's population and its growth due to natural increase.
Younger populations are likely to produce children.
This will both increase the city's total population and lower the median age. In contrast, older populations produce fewer children and have higher death rates which decrease a city's population and raise the median age. In 1994 Darwin had the youngest population with a median age of 29.4. This reflects a tendency for people to move to Darwin for work and leave on retirement. As a consequence of the numbers of working age adults in Darwin, this city also had a higher proportion of children than other cities.