Emily,
As Bintray will be shut down soon, I started converting and migrating all deployment pipelines for projects like JSR 385 that used Bintray and sync mechanism to MavenCentral earlier.
It turns out, that while the last 12 month window of unit-api artifact downloads on Bintray before it stopped counting already was 597.289, the last two months on MavenCentral alone were 779.602, so they were never combined. If you do that, the JSR-385 API had nearly 4.5 Mio. downloads within 12 months.
Not sure, if Eclipse staff or Webmasters (or the owners of particular MP and Jakarta EE specs) have access to the Sonatype stats? They are very neat, even with CSV export so you can easily analyze it in Excel or another tool. Only up to 12 months for normal users, maybe someone at Eclipse could even ask for a different query or do this for all of "jakarta" although what's really useful are the stats per unique API.
Werner