My understanding was that before Rails, Ruby was considered primarily a language used for mathematics. Anecdotally, it does seem that I see a lot of stories about using python for statistics, but I haven't seen any hard numbers one way or the other.
Python seems to also have a lot of web implementations. I'm not sure where you are getting your numbers from.
> The skills and time load sections both re-inforce that Python is more heavily linked to Data Science than Ruby. Ruby is more of a web technology with strong affinity to front-end technologies and iOS.
SciRuby is a great project started last year to bring the same functionality to Ruby.