Attrition

From USAFA Folklore

Attrition was a fact of life at the Academy. Over its history, classes have averaged a little over 30% attrition (for all reasons, both voluntary and involuntary) between Inprocessing Day and graduation. The Class of 1975 had the highest attrition rate in Academy history, at about 46%; the Class of 1998 had the lowest rate, at about 22%.

[edit] Trivia

BCT Cadre are known to tell the Basics: "Attrition is our mission", or "Fifty percent attrition is a job half-done."
Cadets who voluntarily resign are sometimes said to have "punched".