I just noticed something bizarre. If you go to the bottom of the leaderboard on that site, and look at users who only have one game in their profile, and only one trophy earned, it doesn't even add up.
Look at this user, for example:
http://www.yourgamercards.net/profile/Cityrat_HK
This user has one game in their profile, and has earned only on trophy for that game. The percentage complete for that game is showing 1.43%, but the overall trophy completion percentage is showing 2.6%.