That's probably more than I would have guessed at.
I feel it will be higher this year and guess all schools are oversubscribed.
Oversubscription tends to be the normal state for grammars, assuming they've set their pass mark correctly. They need to have more children passing than there are places available so that they can offer a place from the waiting list on re-shuffling (they can't top up with near-misses).
I suspect that if a school is undersubscribed, as Ribston was for a few years due to a high pass mark, then the number of appeals rises in the hopes that the appeals panel will allow more appeals. Ribston must of altered its passmark last year as they were not under subscribed, yet there were just as many appeals as the previous year; I suspect that the playground gossip was 'why not try an appeal - lots got in last year'. It's not peculiar to Ribston - for a few years HSFG Denmark Rd was under subscribed whilst Ribston was over subscribed; at that time, there were more appeals for HSFG than Ribston.
For some schools that I've heard appeals for the number of appeals has decreased over the last few years.
If there's a suspicion that there's more children from private schools who will be appealing due to cashed-strapped parents, I have not noticed an increase over the last few years.