Last year was a totally different game, with iOS completely dominating the tablet market share game, this year, not so much. IDC's market share estimates point for the first quarter of 2013 are out, and they paint a very interesting picture.
As you can see, the top tablet OS market share for Q1 2013 has changed from the same quarter of last year. Android now have the top position with 56.5%, pushing iOS into second place with 39.6%. Apple lost quite a lot of ground in the past twelve months, as this time last year they had 58.1% of the tablet OS market share, leaving Android with 39.4%.
All of Apple's lost ground is sucked into the vacuum that is Android. Microsoft saw Windows' market share increased from 1% last year, to 3.3% this year. In terms of shipments for the quarter, IDC's estimates peg iOS-based tablets (iPad, iPad mini) at 19.5 million units, and Android-based slates (countless companies and models) at 27.8 million. Windows-based tablets saw 1.6 million units shipped and Windows RT-based tablets shipped just 200,000 units.