FOIL success again! The DOE provided the number of waitlist offers made in 2022-23 to students attending 9th grade in 2023-24. It seems like the reported numbers are approximations (rounded to the nearest 10s), but any information is better than none.
You will be able to access these numbers on any school or program page under the “Student & Admissions Statistics” section, right next to the total offer numbers.
I have not requested the 2021-22 data, but the 2023-24 data is supposed to be provided by mid-January. It could be postponed though (it was already postponed once already). Fingers crossed!