A friend of mine (actually college roomate) is head of department at a MAJOR pharm. company. He has been there almost 30 years and heard something in a meeting of all the higher up research docs that floored him and he passed it on to me.
He said they casually tossed around the figure of 20-25% efficacy rate as being "superb". Upon his asking for clarification they told him that 20 - 25 % is "all they could ever hope for in a new drug". That would be a wild success. That tells me that when they give you a drug they are only guessing that it will help about 1 in 4 or 5 people. Another big deal is just how many EXPENSIVE drug trials turn out to be absolutely dead ends. That is big money right out the window. I for one, am glad they keep having a strong financial incentive to keep searching out new and better drugs. Someday I may need them!

Greg