Ruby & Perl are currently at 21% & 18% respectively on Github, so it bears no resemblance to your figs.
I understand what you trying to do by eliminating projects with less than 4 watchers but this is arbitrary figure and the results you produced are therefore affected by this decision.
When you play with population samples then side effects can creep in. You can see this in the difference in Ruby being 35.3% in your figs and it being 21% on Github. Its a big difference and can possibly be explained by things like: http://www.ruby-toolbox.com/
I understand what you trying to do by eliminating projects with less than 4 watchers but this is arbitrary figure and the results you produced are therefore affected by this decision.
When you play with population samples then side effects can creep in. You can see this in the difference in Ruby being 35.3% in your figs and it being 21% on Github. Its a big difference and can possibly be explained by things like: http://www.ruby-toolbox.com/