I love the perl I write, I hate the perl anyone else writes.

Perl is indeed quite polarizing (about 30% disliked, a bit more disliked than .NET). It's just not mentioned often enough to show up on the graphs.

They filtered the data for each by criteria such as top 25 or > 2000. Hence, Python and Ruby but no Perl, or Clojure and Scala but no Groovy.