ResetEra user MauroNL spent some time putting together a comprehensive list of stats and data about the Xbox One backwards compatibility program. Using Wikipedia, Xbox.com and other tools, MauroNL figured out how many games are backwards compatible on Xbox One and how many have yet to receive support. MauroNL also put together some interesting stats about the backwards compatible program.
The current number of games that are now backwards compatible sits at 538 titles. The Xbox 360 has had over 2,000 games released for the platform as of January 2018. This means that roughly 25% of the entire Xbox 360 library is now playable on Xbox One. Of these 538 backwards compatible titles, over half of them are Xbox Live Arcade games. MauroNL also calculated that 37% of the entire XBLA library is now backwards compatible.
Currently, only 33 Original Xbox games are backwards compatible. This is only a sliver of the entire library, adding up to only 3% of the whole 1,047 games that make up Original Xbox library.
MauroNL also figured out which months are the most active for backwards compatibility updates and figured out different trends in how Microsoft has released games since starting the program back in November 2015.
The entire post is a really interesting deep dive into the stats behind backwards compatibility on Xbox One. If you are a fan of stats, check it out.