There's a difference between market share and demand for app developers.

Important distinction: that's 13% of smartphone sales, not total market share. Numbers for sales available here: http://news.cnet.com/8301-13579_3-57355900-37/iphone-4s-inch...

Numbers for total market share here: http://www.macrumors.com/2011/12/29/apple-and-android-gain-s...