We were asked by one of the members in our company, how much is the market share for the open-source software which we work on, Evolution. This was the second time, same question appeared when I was present. As Evolution is the default mail client in GNOME and shipped in many major distros like OpenSuse, Ubuntu, Fedora, Debian etc., we said it should high enough.
But how does one estimate the market share for an opensource software ? Any statisticians who are putting those data somewhere for some popular softwares like firefox, evolution, banshee, open-office etc. after survey?