I know we don't have access to DAW sales (which would be interesting to see), but I thought that maybe using Google Trends might be a good way to compare overall interest among DAWs. Now this is the first time I've used Google Trends for anything, and I've run into a little roadblock, just wondering if anyone can shed some light. 
 
So far I've gotten as far as to add Pro Tools, Cubase and Ableton Live to the comparison, here. When you add a comparison to the chart, you can click "edit" on it and it will offer you some versions of that term. For example, I can add "Pro Tools" as a search term, or as a "software" category item. I figured it best to select "software" for each term - I don't know how this affects the results, but I figured that if you just select "search term" then it'll also pick up a lot of searches for pro tools that have nothing to do with DAW's (i.e. "tools that professionals use"). I was able to select "software" for Pro Tools, Cubase and Ableton Live, but naturally came up against a problem when trying to add Sonar. 
 
Of course "Sonar" as a search term would not do, because that would cover a whole bunch of non-DAW related references to the word sonar. But.....and here's the frigging typical part.....Google Trends doesn't seem to recognize Sonar as software. It offers you Sonar as a "topic" (could mean many different things) or Sonar as a "music festival" (I guess there must be one called Sonar somewhere). So it would seem impossible to rank Sonar as software alongside the other DAW's. Of course I could try "Cakewalk Sonar," but it only offers that item as a "topic" or a "software company." I'm not sure how valid those categories would be in a comparison with other terms that are properly categorized as software. 
 
Anyway just looking at the three DAW's I have managed to compare equally is interesting. Overall interest in DAWs seems to have declined dramatically since 2004. I wonder why this is? Or maybe I'm just not sufficiently clued up about Google Trends to be drawing any kind of conclusion from this data? It's interesting to see Cubase start a lot higher than Pro Tools however. 
 
Also interesting is this map, which shows a clear cut geographical division between interest in Pro Tools (blue) and Cubase (red).