nothing special: it went from 3 mentions to 1 mention over the recording period (a "66.67%" decrease), all the while bouncing off the x-axis but possibly evidencing an upward trend:
It could be an aberration, as one commenter noted there is no smoothing. However, in my own experience of building both Rails and Sinatra apps, I've tended to go more Rails, even for smaller stuff, as it just takes care of more things.