Comparison between Esperanto and Ido
Esperanto and Ido are constructed international auxiliary languages, with Ido being an Esperantido derived from Esperanto and Reformed Esperanto. The number of speakers is estimated at 100 thousand to 2 million for Esperanto, whereas Ido is much fewer at 100 to 1 thousand.
Source: Wikipedia — Comparison between Esperanto and Ido (CC BY-SA 4.0)