thecounter.com also has some global stats that are worth checking out. http://www.thecounter.com/stats/
That's quite interesting seeing that Mozilla only has 3% there compared to the 19% on w3schools.com website Quite the predicament in terms of my dissertation. I think I have to go with the more reliable source of w3schools even though it states that the results are unreliable. It's always a hard 1 when you are using information from the internet because it's such an unreliable source of information due to biasing etc. You have to choose your information sources carefully