In Iraq, weapons are about as previlent as bread. Insurgents have had no problems in arming themselves. In fact it was part of Saddam's battle plan to stash weapons in open areas prior to the the invasion to arm his populace... his game plan was to enable exactly what is going on.
As for the M1, I agree with Charge_7 that you notice it doesn't say "destroyed" not a single M1 was destroyed from enemy fire in the first gulf war although 16 where damadged. So I'd say that especially considering the disparity in what the M1 was designed for and how it is currently being used, it is performing extremely admirably.
Besides, we're talking 80 damaged tanks over 2 years... that's a pretty damned low rate I'd say.