10 - 20 % never exploded, and those exploding buried the unexploded ordnance. https://www.alamy.com/stock-photo-bomb-craters-after-allied-...

Those areas where moon craters at the end of the war. But by then logistics where decentralized, all those last days last ditch products, where made in underground facilities or small village smith factories. Effectively they bombed a bomb disposal pit..