There are 2 articles in JOMFS in 90's that investigated the mean step 1 score of OMFS residents, the pass rate, and the best predictors of success (class rank, NBDE part I and II scores, etc). The study found that approximately 50% of OMFS residents taking step 1 fail on their first attempt. I forgot what the mean score was, but I remember that the greatest predictor of success was a high NBDE part 1 score (I think 94 or higher). I don't think the papers mentioned overall failure rates after several attempts (I would bet this number is quite low).
With 50% of OMFS residents failing their first attempts at Step 1, it's odd that the previous 15 posts put a positive bend on our performance. I don't think that we do poorly, per say. Step 1 is a very difficult exam. The pass rate for US allopathic first attempt is around 90%, osteopathic is somewhat less (I think 75-80%), and FMG's around 50-60%. Given the unique and difficult situation of a 1st year OMFS resident (2 years out of basic science training taught by a dental faculty, fulfilling work responsibilities as an intern, little time to study), I think we do fairly well.