This chart comes from the latest report of the U.S. Army's Mental Health Advisory Team. It shows their research confirms what soldiers have always said, that the more combat they experience, the worse the mental trouble. in cast you were wondering, a "combat experience" means
Threats (IED Exploded Near You)
Fighting (Shooting at Enemy)
Killing (Responsible for Death of Combatant)
Death (Member of Unit Became Casualty)
Knowing this, how can we possibly send young men out to fight again after their 20th such experience?