Yep. The whole quibble over the validity of DistroWatch got me motivated to search for something a little bit better; as it turns out, Wikimedia kindly publishes aggregate stats reports of traffic through its Squid proxies at http://stats.wikimedia.org/wikimedia/squids/SquidReportOpera...

I hand-plotted a few months' of data before deciding it wasn't necessary to go further: from August 2012 to October 2012, Wikimedia saw an increase of 1.1 billion page requests from Linux operating systems (a 10% growth for Linux in that time period); of those, Ubuntu gained 230 million page requests while Mint remained steady at 11 million page requests during that period.

Just to be clear, I would have liked the story that Ubuntu users were flocking to Mint, but that appears to be a fiction at this point.