[dxbydt]

Provenance of data was not in scope, 'twas more of a standard datamining "see if you can dig up something interesting" project. Like I said, there were scores of these - one of my colleagues wrote the famous soda vs pop thingy which once again put location stats to good use- http://blog.echen.me/2012/07/06/soda-vs-pop-with-twitter/