How well students do at any given medical school seems to be a
pretty well hidden statistic. The National Board of Medical Examiners
releases the performance of a medical school only to that school.
Medical schools often use their performance on the USMLEs to evaluate
their courses. Some schools have posted their USMLE score distributions
(for example, The
University of Florida Medical School and The Virginia School of Medicine).
Since performance on the MCAT correlates relatively well with
performance on the USMLE (see MCAT
predicts USMLE scores), schools with the highest admissions
MCATs are likely also to have the highest USMLE scores.
You can find basic pass fail statistics at the NBME
USMLE site
Here's a distribution of scores for all test takers:
Some bench mark numbers (from UC
Irvine Residency Selection Handbook and the NBME
USMLE site):