Late September JMT Permits

Final question (for now!) from Bristol, England. I have a permit from HI for 15 Sept. A friend of mine is thinking of joining me but doesn't have a permit and of course there aren't any to be had of the pre-booked kind for my date. However, I know there are 20 reserved for those who turn up and queue at Tuolumne Meadows. I have a "long" permit - it shouldn't take me 21 days to finish. So he might risk it. However the question. How many people generally show up to get one of these 20 permits in mid Sept? If it's 30 that's not too bad - but if it's a 100, then maybe it's not worth the risk. Thoughts anyone?