Don't know how this lines up against other countries, but it could have something to do with the fact that more than 20% of the federal prisoners are in on low-level, non-violent drug offenses.
So yes. We should absolutely be ashamed of locking people up for no discernable reason.
"We had survived to turn on the History Channel
And ask our esteemed panel, Why are we alive? And here's how they replied:
You're what happens when two substances collide
And by all accounts you really should have died."
-Andrew Bird