Census 2021: How baby boomer kids are making a big bump

The fastest growing age cohorts in Australia are people age 20 to 34 and those over 65, census data reveals. We look at why.

Millennials, mostly the children of baby boomers, are part of a ‘second population wave’. Picture: Lyndon Mechielsen

Australia’s post-2000 migration wave, the sons and daughters of Baby Boomers now pushing into their 20s and 30s, and vast improvements in managing chronic health conditions since the 1970s have reshaped the age distribution of the national population, experts say.

An analysis of 50 years of census data from 1971 reveals large increases in the number of 20-34-year-olds resident in Australia from the mid-2000s.

The number of Australians aged 65-74 is also on the rise.

The data, which plots the percentage difference in the size of the population of each five-year age cohort from the census before, shows there were 13.8 per cent more 30-34-year-olds in Australia in 2011 than in 2006, and 11.1 per cent more 20-24-year-olds at the most recent census compared to the 2016 version.

Among older Australians, there were nearly 16 per cent fewer 70-74-year-olds in 1976 than in 1971, but by the time of the most recent census it was just 2.4 per cent fewer than at the 2016 census.

The data tells two important stories about the nation’s population make-up, demographer Peter McDonald says.

“First, it shows the impact of the big increase in migration in the mid-2000s, roughly doubling from around 100,000 a year to 200,000 or more, and the fact that the migrants coming to Australia are young,” Professor McDonald said.

“Migration was actually pretty low in the early years of the Howard government, but then he twigged to the fact that the population was rapidly ageing, and bringing in skilled migrants was critical for economic growth.

“The reason we are seeing increases in the younger population cohorts is that we are increasingly sourcing our permanent migrants from the international student population, who are usually already onshore.”

Demographer Simon Kuestenmacher.

Demographer Simon Kuestenmacher said there was another reason besides migration for the big increase in the number of Australians aged 20-34 in the past 15 years.

“These mostly millennials are the kids of the big baby boomer generation, so in a way it’s a ­second population wave flowing through,” he said.

“In the coming censuses, it will not be so big as the millennials will have left those age brackets and we will also have missed out on a bit of immigration as a result of Covid’s impact in 2020 and 2021.”

Among older Australians, the data shows the consistent progress made in stopping people from dying early, Professor McDonald said.

“A lot of it is lower heart ­disease,” he said. “There is far less smoking and better lifestyles, and the technologies and surgery have dramatically improved.”

Mr Kuestenmacher said the numbers of people in their late 60s and 70s was also growing simply because the baby boomers were now reaching those age brackets, with the oldest boomers now aged 74.

“The fastest-growing population cohort in Australia is people in their 70s,” he said.