This is what I've heard. I was curious whether it had changed much over the years - particularly the foundation candidates, with which I am less familiar.
This brings up a rather elucidating point, although it is certainly not very encouraging to those who seek admission to the Naval Academy. In an average Plebe class of 1200 (although, during eras of downsizing, it is trending toward less than 1200), 275 of those spots are already taken by NAPS/foundation candidates. That leaves 925 vacancies. Some of those are recruited athletes with the academic credentials for direct admission without the necessity of a preparatory school. They are going to get an appointment one way or another. I don't know how many that is - maybe 100? That estimate may be a bit low. That leaves a little over 800 vacancies remaining with nearly 20,000 applicants.
It has been said to many who earn an appointment, "That's the easy part. The next four years will be the hard part." Statistically, that is untrue. Roughly 7% of those who apply earn an appointment. Roughly 85% of those who earn an appointment go on to graduate.