Look at this two pictures (screenshots of my github's repository):
The first one is the percentage that appears in my first view of my repository..
The second one is the really programming languages that I'm using. As you know you can go inside your projects and can see how many files of the different programming languages have. I'm only using 58 files of css (you can't see it because is selected.. but only 58 files)
Does anybody have any idea why GitHub is doing this awesome thing?