Looks like it was about 50% in 2014-2015, but has dropped in recent years. Just to add, there are loads of outstanding claims from 2014 on (more than half). You could read that a bunch of ways, so take it with a grain of salt. Also note the appeal rate for all year for rejected claims is about 10-15% acceptance for all countries. It seems once your claim is denied, you are almost putting off the inevitable removal.