According to redditor e8odie, 98% of Australia's population lives in the white area. The remaining 2% sprawls over the vast, sparsely populated interior. I can't verify the origin of this map, but the claim seems to fit with other population maps of Australia that I've found online.
This is one of 40 fascinating and unusual maps featured at Twisted Sifter, including maps of internet usage, most common surnames and per capita coffee consumption. You can view them all at the link.