That's because Python is actually used extensively in the West outside the context of web development. Ruby really isn't. Rails became popular, and people decided to learn Ruby so they could use Rails. Most people who choose Python web frameworks do so because they are already familiar with Python.
But I agree, I learned Python because it seemed like a great language, and learned Django because I was moving into web dev after years of other work with Python. I don't believe I'll ever pick up Ruby for anything other than learning Rails (and I doubt I'll even do that, since Python is so similar).
Just take a look; the django bar is not even a bar, more like a square. Rails seems to have a 40:1 edge over Django in popularity.
The other thing you will notice is that India is where Rails is most popular; but try to pull back the timeline slider and play with it a bit. See how different countries discover rails at different times but soon after lose interest? Except for India, it stays popular there.
I'm not sure what your link is trying to show, actually.
But note that most people searching for Django will use only the name Django, whereas Rails is often called "Ruby on Rails", meaning searches for "ruby and rails" will naturally tend higher than "python and django". Again, I'm not sure I understand your point, so I don't know if this means anything.
This is an answer to a question that grasshoper is not asking: he claims that Python is used extensively "in the West" in contexts other than web development.
Comparing search traffic for django/python to ruby/rails has nothing to do with this.
