Recent web accessibility survey?

Hi everyone, 

I am looking for information about the current state of the web. I have heard figures bandied about that the web is 90 to 99.9 % inaccessible, and would like to know how these were arrived at. 

I was particularly hoping that somebody might know of a web survey that catalogues the problems of the web. The only one I have been able to get my hands on was done in 1996, and in web time that puts it about two decades ago! ( I once heard that web years last 2.6 months)

If any of you nice guys out there feel like helping out, I would be very grateful. 

Thanks 

Gareth Parkinson