http://qa.debian.org/popcon-graph.php?packages=git++git-core...
With CVS, darcs, monotone also interesting.
I keep tacking RCS onto the ends of these, too :) It keeps surprising me - Mercurial passed RCS ~ last June, and Bazaar passed it in roughly June of this year. It gets a lot of usage still.
I use it pretty often for casual alteration of configuration files.
http://qa.debian.org/popcon-graph.php?packages=git+git-core&...