Going by release date in the OCG, Arcana Knight Joker is actually a GX card. (It was released within a week of Cybernetic Revolution.)
As for the 99% not being GX thing... While the majority of the stuff here isn't GX-era, it makes up a lot more than 1% of the set. Off the top of my head, I think it's something like 10% of the set.
Anonymous
