Trees spread naturally over time, they'll grow around anywhere the player visits, but only on grass and dirt areas, not concrete or any man-made tiles or sandy deserts etc. This originally was msakuta's mod! I simply patched it to version 0.16 of Factorio.
Counted when a user downloads a mod release for the first time. Before Nov 2021 it counted everytime a user clicked the mods download button.
Counted when a user downloads a mod for the first time. Has no data before Dec 2022