Home in Iowa-25% offhand(hopefully with a tree to rest on), 50% sitting either in a stand or on the ground and 25% kneeling. Can't recall ever trying a prone shot on big game-the terrain I hunt just wouldn't allow it.
Hunting out west probably 75% prone (equally divided between off a pack and off a bipod. 25% sitting or kneeling-always with a pack, bipod or sticks.