Know-How Exchange : Research/Metrics

I am doing a competitive analysis for an internet registration authority. Individuals around the world have some measure of choice as to which domain extension they can use e.g .org, .com, .ca etc; These are called generic Top Level Domains (gTLD's) and i am looking for any kind of market info on this category such as market share, strengths and weaknesses, # users etc; any kind of quantitative or qualitative info would be much appreciated as i am running into a blank wall on this. i am not looking for info on internet usage in general (there is lots of this out there) i need very specific info on gTLDs.