2011 RH = 50 appeals, 31 successful.
2010 & 2011 were both unusual years for Ribston appeals. It started with the pass mark was set higher than previous years; I have no idea why - these things happen. The school was therefore undersubscribed by quite a lot.
When it came to the appeals, as my cloudy mind remembers it, the school didn't put up a strong case against allowing the appeals so the ones who had good academic evidence were likely to have been upheld. Chances are if the pass mark had been set lower, most of those allowed would probably have passed (apart from ones who had major problems on the day).
From what I've read, for 2012 the pass mark returned to a normal level, so the point at which 'appellant vs school' tips away from allowing the appeal was probably lower and less appeals allowed. However, the 'playground bush telegraph' still erroniously says that "Ribston allows loads of appeals so you'll win even if you say your daughter's pet chuckiepig had a bit of a sniffle the night before the exam and she was awfully worried about it".