On the web, you'll likely find a lot of speculative information by individual people as to how popular any given DAW is. I remember reading a post some time ago where someone said that Logic was more popular in Europe than in the US. That's dubious, since they didn't cite any numbers.
That said, no harm done in trying to find out some stats by searching the web. But really, your best bet would be to contact individual companies and see if they'd be willing to share that kind of information with you.