Those per piece counts can't be from the same data as post #56 above.. right?
Sure, but I divided by the total number of pieces on the board: 16 pawns, 4 rooks, 4 bishops, 4 knights, 2 queens and 2 kings. Double checking, there seems to be a typo on the rook moves (should be 2195), and maybe I rounded wrong on the king moves. Good enough for government work.
I was trying to puzzle together how double checking could possibly have skewed your results, but then I realized you meant double-checking, not double checking.
What about promoted pawns? Do those count as pawns or the piece they became? What about on the move they actually promoted?