Have you ever tried google trends? It's a fun utility to see trends in search keywords typed in google. You can go as far back as 2004, so there's plenty of data available. You can even compare different trends.
One of these interesting trends Pascal once pointed out is c# vs ruby. Back then, this is what it looked like (c#, ruby)
The blue line is c#, the red line is ruby. And what do you think the regular dips are? WEEKENDS!
And what's more, the ruby line is close to the c# line in the weekends. Does this mean that there are almost as many ruby developers as there are passionate c# developers? Maybe. It certainly seems to be a trend, but let's not be hasty about such conclusions. After all, I'm not looking for a flame war here.
Lets look at the current trend for the same keywords:
Aha, now ruby is perceptibly more popular than c# in the weekend. This data supports what I've been suspecting for a while now: Ruby is on the rise worldwide. I quite like this idea.
Lets see what this means in our small country - Belgium:
Wow: 0 hits for ruby? Ok, that can't be right. Probably because searches in Belgium go through www.google.be. Tried the same on google.be => same result. That probably means that the search terms for c# are WAY out of the league of Ruby in our small country. Does this mean it is time to jump on the Ruby bandwagon, because Belgium will be catching on, and now is the time to build expertise in it?
All in all, a fun aside in trying to decipher what these numbers and graphs mean, with maybe a little confirmation bias on my part.