Have a look here. http://en.m.wikipedia.org/wiki/List_of_cities_in_Australia_by_population
40% of the population live in 2 cities - Sydney and Melbourne. Another 20% live in 2 more cities (Brisbane and Perth) and 5% in Adelaide. That's 65% in just 5 cities. You only have to get down to position no. 11 to be less than 1% of the population. You get the idea.