It really depends on how people performed on the paper. For our double award science, the A* grade was only 73%, this is likely to mean that the paper was pretty difficult (I myself thought the same thing). In our additional mathematics, the A grade (which is the highest grade for FSMQ) was only 69% and even then, 75% of people who took the exam did not achieve that grade which also must have mean that it was a difficult paper.
So, as repeated in the beginning, I think it depends on how people performed on the exam so it can range from just 70% to some evil high percentage of over 90%! =(