Appointment and Graduation are the two numbers that are commonly reported. I heard Supe/Dant brief a couple months ago that something like 10-11 left during Plebe Summer. (That is an incredibly low number, almost unbelievable to us old timers). Beyond that, there is probably no official tally, as it is a moving target. There are a handful that leave during the course of the first couple years, perhaps a small jump at the end of 3rd Class year as 2 for 7 approaches (I would be curious how many leave at that point), and then pretty steady through graduation (perhaps a handful of Ac Board, Conduct and Honor departures). The main point during the Supe /Dant briefs is that the emphasis is on retention. The quality of the incoming Class is high, and everyone appointed has ability to make it through. I think overall attrition rates are in the in 10-15% range (as opposed to 30% range 20-30 years ago).