Not sure why you'd want to learn Ruby/Rails. Ruby has been dropping in use for a few years now, and it looks like that downward trend will accelerate.
Have you considered Python/Django?
Have you considered Python/Django?
Indeed.com shows no such drop in Rails job offers. Both Rails and Django are showing growth in the percentage of job offers: http://www.indeed.com/jobtrends?q=rails,+django&l=
If you fall back to a language-only search, then Python shows a bigger slice of the pie, but the original question was about web frameworks. http://www.indeed.com/jobtrends?q=python,+ruby&l=