To your question, and I stand to be corrected, my understanding is that the general answer is most. Part of it is the reason I highlighted. One of my concerns is not just the rejections, but how long it takes after a positive recommendation. It ranges, in some cases, to several hundred days, so one would presume that there is something happening during all that time, and again, it's another review. That's why I talked about the three levels of review for the same drug.
On April 16th, 2007. See this statement in context.