The graph is bugging me. Around 85 people born in 2009 and 35 people born in 2008 do not use mouse inversion... We have 1 and 2 year olds playing first person shooters?
The registration form on the ESL website doesn't have any validation for the birth date. If you leave the field blank, it's set to "today" - That's where the 2009/2008 etc people come from.
The site is using you registration date as birthday if you don't change it.