According to Matt Rosenberg, in this:
http:/geography.about.com/od/populationgeography/a/popdensity.htm
90% of the population occupies 3% of the land. Land covers 29% of the globe.
.03 x .29 = .0087 = .87% Let's call it 1%. Therefore, if Mr. Rosenberg is
correct with his data, I believe it's very safe to say that less than 2% of the Earth's
surface is inhabited by humans.