And I once read that in World War One, 25% of planes were downed due to mid-air collisions during dogfights, as often with friendly planes was with the enemy.
Just in flight training we lost over 20,000. Do your remember the movie, I think, "It's A Wonderful Life?" There was a actor, who won an Academe Award, and had two arms blown off? Well he had it happen during demo training at Ft. Bragg. I suspect we lost one in ten due to training, and non combat.
Lastly, I don't believe the being issued real ammo, and firing it thinking it was fake. Fakes have no bullets, just crimped brass cartridge filled with powder.