In a recent analysis conducted by Gamasutra, it appears that the Valve's Steam has already seen more releases in 2014 then all of 2013 combined. Just under 200 games were released in April alone.
The Greenlight and the Early Access systems, released in Summer 2012 and March 2013 respectively has played a big factor in the increase of game releases on the platform. However, the process has experienced some criticism due to the release of The War Z, which resulted in the games removal from the store.
Valve does intend to get rid of the Greenlight process in the future, and convert the store into an open-publishing platform, making it a lot easier for developers to release their games.