Among the other distributions, Debian has the fastest growth in absolute terms, and is secure for now in second place. But some of the smaller distributions are growing faster relative to their existing user base. Gentoo continues to roughly double each year, albeit from a low base. Mandrake’s recent acquisition of Conectiva will boost it only slightly, as there are only a few thousand Conectiva sites in the survey; Mandrake’s own growth is more significant.

See here and here for past articles on Linux distribution growth.