You can't really compare it to Black/White though, that game wouldn't be X/Y's equivalent game. Black/White was the second generation of original games for the DS. Naturally pre-orders were higher, because the install base was higher.
You should, however, compare X/Y to Diamond/Pearl, the first generation of games on the DS when that too had a smaller install-base and is thus X/Y's equivalent. As far as I know, X/Y is tracking ahead of Diamond/Pearl.







