Debian has several developers who do work on the kernel. Ted T'so comes to mind. Problem for this kind of study is how to categorize such a person. Does Ted work for IBM, or is he a Debian developer, or is he a core kernel contributor? Well, all three. So who gets credited for his work in the statistics? Personally, I think that Ted should. We don't say that IBM, or VA Linux, or Debian is a major force behind ext3/4. Ted is. If the stats don't reflect this, there's something a bit fishy about them.