Before you get attacked (and you will) it is imperative you use the search function on this site because this has already been discussed. In addition you are in the wrong forum and site to be discussing this. Go to this website www.marineocs.com
It is specifically for people wanting to become Marine Corps officers. Good luck on your journey!
P.S. Injuries is a pretty common factor (word on the street), but hey I'm a Parris Island Marine
I started with 66 and graduated with 43 if I remember correctly. Rate is pretty high obviously. Probably had 5 people drop on request, a lot due to injury. The rest got sent home to due to failing academics, poor leadership, stuff like that.