I don't know why I do this. (contribute to a wankathon), Boredom perhaps, but;
Given Australlian land mass 7.5 million sq kilometers.
x 500 ft intervals to 20,000 ft = 40 x 7.5 = 300,000,000 (million) sq kilometers. Some of you bokes want to "own" this all, because an Auster with a turbocharger might bite you on the bum. Whats the odds you gamblers? I met a Chinaman at the casino the other day that will give odds. Worked out pretty much in his favour but.
Stick to the "J" curve if you must, but leave us in the boonies alone.
Space travellers excluded of course.
Above FL 200, do your own thing.