Cultural trend of population growth with household size decline
Household sizes are dropping, and this is largely because of the need for 2 people to work to save for a deposit. Other factors are the time and cost burden of multiple children with 2 people working and marriage being consistently in decline. The tread line from 1986 – 2016 end with families making up 71% of Australia’s households, in 1986 it was 77%. Over this same period, the number of single-person households increased from 19% to 24%.
https://aifs.gov.au/research/facts-and-figures/population-and-households
Meanwhile, couples with children are having fewer children. In 1961 the fertility rate was 3.55; in 1990 it had fallen to 1.90. https://www.macrotrends.net/countries/AUS/australia/fertility-rate . It was 1.58 in 2020, the lowest ever. https://aifs.gov.au/research/facts-and-figures/births-australia. And back to 1.70 in 2021. https://www.abs.gov.au/statistics/people/population/births-australia/latest-release. In fact, Australian has had a sub 2 children birth rate per woman since 1978. Migration is the cause of our slow annual population increases.
This 1.70 children can be compared to 2.3 children today globally.
At the same time, the percentage of couples without children has increased from 28% in 1976 to 38% in 2016. And single-parent families have also increased – from 6.5% of families in 1976, to 10.2% in 2016.
By 2016, that average number of people per household number had fallen to 2.6, this slow decline was first measured from as high as 4.5 in the early 20th century. As of 2021 Australia had an average household size of 2.59 people.
https://www.globaldata.com/data-insights/macroeconomic/average-household-size-in-australia-2096118/
Regional Australia households have also contributed to the 2021 single-person households increase. In 2021, 28% of households in Regional Australia contained only one person, compared with 25.6% for all of Australia, with the most dominant household size being 2 persons per household regionally.
https://profile.id.com.au/australia/household-size?WebID=245
This rise in single and dual person households is a data point which could be its own topic, but for the sake of this data dig just keep in mind, single households allow for only for 1 income stream, and could be a factor to attribute to lower average household earnings.
In the era of 89 and 90, at the time of the 1986 Census, there were 5,264,516 households in Australia. The average number of persons in each household has been declining gradually for at least 100 years (Hugo, 1986). For example, in Victoria in 1891, there were more than five persons per household on average (McDonald and Quiggin, 1985); by 1986, the figure had fallen to 2.9 persons per household.
At the 1991 Census, the number of households had risen to 5,852,518, an 11 per cent increase since 1986 in a period in which the population increased by only eight per cent. Thus. the average size of households is continuing to decline.
Based on the above we have estimated household sizes to be 2.85% for the 1990 timeline.
The two-person household was the most common type recorded at 31 per cent and together with one-person households, these small households constituted 51 per cent of the total.”
https://www.abs.gov.au/ausstats/abs@.nsf/Lookup/72DC873D21F1E2ECCA2569DE00221C82