The data is from AAMC. I asked them for the historical data and they gave me two attachments for the past two cycles. For the current cycle, the data can be viewed at
2020 FACTS: Applicants and Matriculants Data
When I stated that I believe the WL list is longer, I mean more people are on it. I think they (and other schools) needed to build in the cushion because so many applicants applied to more schools. To me, it was interesting that the total number of applicants actually decreased this year.