Steam adds Global Achievement Stats

Steam is offering community members Global gameplay stats for all games that have Steam Achievements, showing what percentage of players have unlocked each achievement within a game.

Some good examples of achievements not being unlocked due to insane difficulty include Braid's Speed Run which has only been completed by 0.6% of users who own the title, and Left 4 Dead's Legendary Survivor achievement, which has only been mastered by 0.4% of all users.