From what I have been told by a friend who runs a busy school only 1 or 2 out of 10 carry on to complete the course and if you take into account the guys that turn up for a couple of trial lessons never to return and then tell their mates in the pub they are learning to fly Helicopters it is probably 1/100 !
They often drop out due to money, ability, fear and in the UK weather !
E.