Although their population is small compared to other overseas-born groups, the rate of increase - nearly 28 percent a year, on average - is well above other groups. For example, the next fastest growing groups - those born in Pakistan, Brazil and India - increased their numbers by around three-fold over the same period. The steepest decline among the top 50 countries of birth was for Serbian-born residents, followed by those born in Poland. As the chart above shows, the share of Australian residents born overseas last peaked in the late 1890s. Nearly 30 per cent of the population were foreign-born at the time following the first mining boom and the surge in Chinese migration in the gold rush era, according to Anna Boucher, a senior lecturer in the University of Sydney's School of Social and Political Sciences. "Then there was the introduction of 'White Australia' and the effective closing of borders, with the exception of some Commonwealth migration, up until the post-war period," Dr Boucher said.

This explains the steep decline in the share of overseas-born Australians during the first half of the 20th century. The dramatic turnaround in the mid-1940s reflects the shift to a mass migration policy, driven by a belief that Australia must "populate or perish" to survive in the post-war era. A new migration scheme aimed to increase the population by one percent a year. The dip in the late-1970s relates to low migration intake under the Whitlam and Fraser governments. Since 2000, the figure has risen steadily. "The story there is around bipartisan support for temporary migration," Dr Boucher said - in particular, rapid increases in the number of working holiday makers and international students. Australia ranks fourth among OECD countries for the largest proportion of overseas-born residents, behind Luxembourg (43.7 per cent), Switzerland (28.3 per cent) and New Zealand (28.2 per cent) according to 2013 statistics from the Organisation for Economic Cooperation and Development.