The thing I don't get is, isn't the Windows App Store only available to Windows 8? Microsoft definitely haven't sold a billion licenses to Windows 8, so where does that claim come from?
That would be a "potential" amount of Windows 8 users. Not now, but in the future.
I can't say that them having to resort to using imaginary amounts of future users would make me feel any safer about developing for their app store.
And that probably means that Android outsold Windows this year, or else they wouldn't have used "last 2 years". Going by Android's growth rate and Windows' saturation, i would say this is a good guess.
http://www.avc.com/a_vc/2012/12/mary-meekers-2012-internet-t...
for the overall trend. Counting all computing devices - PCs, smartphones, tablets (and that's what matters in the app market) - Windows used to have 95% of that market, but iOS and Android are quickly reducing that and the Windows figure is now 35%.
The last time Windows had such low market share was around 1984. But then Windows was rapidly rising, today it is rapidly declining.
Stuff I kind of sort of already knew, but numbers and charts really bringing home the magnitude of some of the changes, challenges, and opportunities in front of us.