I don't know about most 10s although you may well be right.
The most 40s is for showdances with 5. Obviously that's different so the most for a specific dance is shared between Charleston, Salsa, and QS, with 4 each. Of course, there are some dubious 40s among them but let's not go there.
Charleston is the best dance for a 40 based on this since it was introduced most recently. QS has been there since the start. Salsa is in between those two. The only surprise is possibly the Salsa. Or is that just recent events and the Abbey 40 that is causing that.
If the Charleston isn't highest in 10s overall it is likely the highest proportionately given that it has been danced less often than most others. Even though Aliona said it is easy because you can get away with murder doing it.