Sadly, I am sure you are correct. It is very under-reported and there are a lot of cover-ups.
My college has on its rulebooks that sex is grounds for expulsion, just so when some jackhole tries the "I had sex w/ her, but didn't rape her" defense they can still technically expel him. ;-) And since the University is its own little fiefdom, they also figured out a way to punish them through both the school and the regular law w/o any double jeopardy issues.
The administration and the campus police were in complete agreement about the severity of the issue and weren't afraid to take a stand (rare in academia), but incidents still happened far too frequently and didn't get reported.
Mama Scooterbug worked in the Psychology Department at a big University and had some truly horrific cases. Nothing like a frantic call at 3am asking if you have pepper spray because some girl was raped and left for dead in a dumpster to make personal safety lessons hit home. :(