@box464 I think this is also showing a change in how albums are released: with CDs and the previous technologies, an album always had 10-12 tracks, or a specific length. With streaming services, there is more of an incentive to release tracks individually, so they can be advertised independently to reach more people. It is a pretty common pattern: artists nowadays release singles, then an album with all of them, which, depending on the definition of "album" in this chart, can result in 5-6 times more releases.
To draw real conclusions, I think we should look at the number of individual tracks being released per year (Spotify links them together if they are released in different albums)