It's not sales or installed base share, it's browser share.
I could put the difference down to just iPads, which apparently have much higher browsing rates than mobile devices, but the numbers don't agree there either e.g. my source has iOS as lower than Linux whereas your numbers has it as twice as high.
(Once you add iPad numbers you start to wonder why netbooks aren't included and then the fact that iOS and Android numbers total are dwarfed by any single version of IE begins to make it seem ridiculous.)
I could put the difference down to just iPads, which apparently have much higher browsing rates than mobile devices, but the numbers don't agree there either e.g. my source has iOS as lower than Linux whereas your numbers has it as twice as high.
(Once you add iPad numbers you start to wonder why netbooks aren't included and then the fact that iOS and Android numbers total are dwarfed by any single version of IE begins to make it seem ridiculous.)