Australia's population is growing at its fastest rate in nearly two decades, thanks to rising fertility rates and an immigration boom bigger than that during the aftermath of both world wars.

The number of Australians grew by 1.5 per cent, or 315,700 people, over the year to June 30, topping 21 million for the first time.

Australia now ranks above the world average for population growth of 1.2 per cent, and only just behind the rapidly expanding Indian population, which is growing by 1.6 per cent and expected to overtake China by 2050 as the most populous country.

Of the two possible sources of population growth - immigration and natural increase - it is immigration that is driving the population surge.

http://www.smh.com.au/news/national/migration-boom-swel...4/1196530678741.html