TL forum account names are stripped of non-alphanumeric characters and searched on sc2ranks.com. A case sensitive match is then performed on the results and the highest ranked account is chosen as the best match.
You can view all the charts here Below are some descriptions of the more interesting charts.
This chart shows the different game types that people play. Keep in mind that users can fall into multiple groups so 44.1% for 1v1 does not mean only 44.1% play 1v1. Not the most useful chart but still somewhat interesting.
This chart shows the number of players who play 1v1 vs the number of players who only play team games.
This is the race distrubution of TL users for 1v1. The distribution is incredibly even and there's even a high percentage of random players as well.
This final chart needs to be taken with a grain of salt as the methods I used to match players with their corresponding Battle.net profile gives each player the highest ranking match. For example, if a TL user named Zeratul matched with two accounts: one masters, the other silver, it will assume the masters one to be the correct account. Regardless, this chart does reveal a pretty even distribution of skill between platinum and masters with the average skill level being somewhere between high platinum and lower diamond.