Wow! I must admit I was rather surprised by the per-subsection numbers. Intuitively, I would have expected more churn in the drivers section (ie. as new drivers get added, old ones removed (ok, that's pretty rare) and wide-spread API refreshes) than in, say, the core kernel.
Quite the opposite is true, though. The core kernel has the lowest percentage, weighing in at 13%! The drivers directory, on the other hand, is way out at about 30%.
The math doesn't work for me, though. How can the whole kernel be at 41% if only one of the subsystems (sound) is noticeably above 41%, Documentation is tied at 41%, and the rest are below? Even fs, net and include (which are near 40%, but below it) should bring the average down. And isn't drivers (which weighs in at ~30%) pretty much where the vast majority of code lives?
Is there some other half-million line dreadnaught hiding that's not captured in the subsystem graph, anchoring the average at 41%?