The information makes a lot of sense.
Pawns definitely move the most.
Knights jump around a lot, especially in the closed positions
Rooks move almost all the time in rook endgames
Bishops like outpost, fianchettoed or traded off.
Queens don't move that much until the endgame
Kings don't move that much until they do a little in the endgame
It seems obvious from the data that pawns are used the most, but before I saw that, I would have said knights. They seem to make most of the attacks, at least early on in the game.