Just one week before World Metrology Day 2019 and shortly before the Public Review of JSR 385 the combined downloads of Unit-API (JSR 363 and 385) exceeded the 100-thousandth download within a period of 12 months:
111k Unit-API downloads

See Bintray statistics:
https://bintray.com/unitsofmeasurement/maven/javax.measure%3Aunit-api#statistics
Click "1 Year" date range.

Currently the vast majority are JSR 363 downloads, but once JSR 385 goes Final, we expect to see more of it and probably even a higher total number across both versions.