Not sure I would conclude that debain (or ubuntu to a lesser extent) is "Stagnant" from this data. The count seems to track quite positively w/ each of their release cycles -- every 6 months or ~2ys, respectively, and then settles back down thereafter; however, over all it looks like an upward growth trend (ok, w/ the exception of Ubuntu (fr), but that list has only ~1/10th that of the ubuntu(en)).
I think this might be a better metric for stability or reliability of the distros, rather than their health: I suspect many people only sign up to these forums when they want to ask for help with a problem. Anecdotally, over many years as an Ubuntu user the only times I've ever visited their forum were when I had problems after an upgrade (and it was usually with WiFi).
Anyone know why there is a steep drop as we move towards the end of 2011?<p>For some reason, this trend seems to be uniformly noticeable in most distros.