What are the relative market shares of the various desktop GISes? I'm interested in this within the open-source and non-opensource realm.
One article that I read, is that the market share of ESRI is estimated to be approximately 30% of the global GIS market in 2009 (Daratech, 2011 - dead link unfortunately) but that they have a much higher perceived 'mind-share' (Batty).
I started thinking about this as I wondered which was the most popular open-source GIS program, and assumed it was QGIS but I'm finding it hard to locate any numbers.
To clarify (in response to a comment), I am interested in GIS Desktop tools that allow quantitative analysis (which would exclude Google Earth).