That's not necessarily true. A lot of those were sold to new divers who never used anything else (I was one), or experienced divers who bought all new gear for some reason and ended up with the Air2 for one reason or another (such as being included in a package). That's a bit different from the question I asked - that is - the percentage of Air2 users who specifically decided, "I've been using this octo right here, and now I am going to ditch it and go get myself an Air2".
OK, probably Lots and Lots. Have no clue where you can come up with stats on this. So thats my answer.