I work in a non tech driven city and I'll say a lot of the academic based companies lean towards python. Most likely because it's the language they were taught on in school. I will say that a lot of the more hungry companies that are a bit more lean use node. I know a handful that use clojurescript and the rest are either php and ruby with some sort of npm stack controlling the front end.

I could imagine sf to be a lot more node heavy though given that they take the technical stack a bit more serious than other companies. Uber for instance uses node, but the job available in my area required a python understanding. I can see it trickle into more jobs as the education of the benefits of node bubble up to management and the availability of a javascript workforce becomes more present.

It might be hard to compare. What metric would you want to see for your comparison? Also, do you only want employed or also self-employed? Could you further explain what you mean with "works with the supply and demand on a daily basis"? The way i read this, many people hired in many a business doing their coding never has to do with this. That's mostly up to sales. But for self-employed developers this is just business.