This market share might be data that is of interest to a number of Sketchup users/ developers.
Can I suggest setting up a simple survey (one question, tick the boxes)?
The Sketchucation admins may be prepared to co-operate, or you could set up one on something like Google Forms (I'm not a fan of Survey Monkey, but its a possibility. You would need to promote i on the other sketchup sites/ forums, for completeness.
My only request is ... if you do this - make really simple; as above.