Strange...
"Apple's iOS will still be holding on to the top slot, accounting for 57.8 per cent of the tablets that ship in 2017. Android's share of tablet shipments will have grown to 33.4 per cent by then."
But Android tablets already have 27% in Q3 2011, and iOS is already down to 66.6% according to this article:
http://www.reghardware.com/2011/10/21/android_and_apple_dominate_world_tablet_market_in_q3_2011/
If that is correct, the 33.4% market share will most likely be reached by Android tablets in Q4 this year, not in 2017.