While it may be true that 89% of Antartic ice sits on land, 89% does not qualify as "virtually all". 11% is still a surprisingly large proportion. I didn't think it was quite that large.
BTW, the map is from the CIA fact book? You just can never tell what those guys have exhaustively investigated, or what they've ignored.
Okay, fair enough. How about most or the vast majority? In any case, the ice is predominantly on land and I'd bet that most of the ice shelves are resting on the bottom where the water is not yet deep enough for it to float.