The release of the historical population data by the ABS allows us to look at where we've come from to where we are today - with a demographic spin.
Since 1926, the Australian population has grown considerably, both in size and maturity.
Using 30 years to approximate a generation, this blog looks at three generations of change since 1926, and one generation into the future - 2046.
Population growth 1926-2016
In 1926, the Australian population was 6.06 million.
By 2016, it had almost quadrupled, reaching 24.19 million.
Over this 90 year period there has been considerable variation in the pace of growth.
Throughout most of the 1930s the rate of population growth was less than 1% per annum.
Since then it has only fallen below 1% on two occasions - 1942-43 (the height of WW2) and again in 1992-93 (economic recession).
The most rapid periods of growth have been in the 1950s and 1960s, the so-called baby boom era.
Not only were fertility rates very high, but growth was also driven by high levels of overseas migration, particularly from European countries.
Throughout these two decades the annual population growth rate often exceeded 2% per annum.
Growth rates declined in the 1970s, and a 2% per annum growth rate was not recorded again until 2007-08.
Changing age structure
The graph below shows the age structure of the Australian population every 30 years over the period 1926-2016.In 1926 and 1956, Australia had a youth age structure, with high proportions of children and young adults.
In 1926, almost 40% of the population was aged 0-19 years, decreasing to 36.1% in 1956, 31.5% in 1986 and 25.0% in 2016.
Despite the decline in the proportion of young people, it's important to note that they still grew in size.
There were 2.39 million persons aged 0-19 years in 1926, and 6.05 million in 2016.
Conversely, there has been considerable ageing of the population.
In 1926, just 5.3% of the population was aged 65 years and over.
This proportion increased to 8.4% in 1956, 10.5% in 1986, and 15.2% in 2016.
In 90 years, Australia has gone from around one in twenty persons aged 65 years and over, to around one in seven.
Numerically, this group has increased eleven-fold, from 319,000 to 3.67 million, or around four times faster than the total population.
Why have these changes in the age structure occurred?
There are a range of reasons, ranging from health and sanitation improvements, to changes in fertility rates, and increases in life expectancy.
From a demographic perspective, the increases in life expectancy are interesting.
In the early part of the twentieth century, most of the gains in life expectancy were gained through improvements in infant mortality.
This meant that more babies and children survived, particularly as infectious diseases were brought under control.
More recently, improved survival rates at the upper end of the age spectrum have meant that more and more people are living to very old ages.
Changes in the age structure matter because age is often an indicator of demand for services eg child care and aged care, as well as age friendly attributes in a community eg play equipment in parks, street furniture and improved walkability.
What does the future hold?
What will Australia look like in another 30 years?
Let's go forward for a moment.
The ABS produces population projections every five years, generally after each Census.
The latest series has a 50-year horizon, projecting out to 2066.
Population projections are essentially the outcome of a set of assumptions about the future direction of the components of demographic change ie births, deaths and migration.
Of these, migration is the most difficult to project accurately due to its volatility.
The ABS produces a number of projections with different assumptions, but generally Series B is considered to be the "medium" projection.
The ABS describes this series as a continuation of current demographic trends ie fertility rate of 1.8, life expectancy of 83 years for males and 86 years for females, and net overseas migration of 225,000 per annum.
The Series B projections for Australia indicate a population of 35.7 million in 2046.
The realisation of this number will mean an almost six-fold increase in the population since 1926.
The age structure will continue to change, with even higher proportions of older people in the population.
The tail end of the baby boomer population ie those born in the early to mid 1960s, will be in their 80s in 2046.
The graph below shows the difference in the age structure between 2016 and 2046.
In 2046, 18.8% of the population is projected to be 65 years and over, up from 15.2% in 2016.
However the most dramatic changes are for persons at the upper end of the age spectrum.
Persons aged 85 years and over are projected to comprise 3.5% of the population, compared to 2.0% in 2016.
In 2046, this cohort represents the bulk of the baby boomers, as people who turn 85 in that year were born in 1961.
Of course, whether these numbers will eventuate remains to be seen.
Population projections are notoriously hard to get right, particularly due to the volatility of overseas migration.
The key is understanding the assumptions behind the projections and how they influence the outcome.
Summary
The Australian population almost quadrupled in size between 1926 and 2016, from 6.06 million to 24.19 million.
The Series B projections produced by the ABS indicate a population of 35.7 million in 2046.
The major changes in the age structure since 1926 have been a decline in the proportion of young people, and a corresponding increase in the proportion of older people.
Several factors explain the changes in the age structure, eg reduction in infant mortality, improved health, declining fertility and volatile levels of overseas migration.
