You know what would be a very interesting statistic?
Take all windows PCs, look at usage of non-IE browsers, then take all Macs, look at usage of non-Safari browsers, then take all Ubuntu PCs, look at usage of non-Firefox browsers. Tally it all up and you'll have a reasonable gauge of popularity, where "popular" is defined as "people actively choosing this browser over the default one".
I strongly suspect Chrome would utterly dominate that statistic.