No expert, but I always thought Ubuntu was probably the distro least likely to have a large % of GNU thanks to all the extra stuff that comes with it. Would be interested to see this for Debian or etc.
I think in terms of a standard desktop user's install, a Debian machine configured for usual use is not going to differ all that greatly from an Ubuntu machine. A server config forsaking much of the user-friendly stuff, maybe.
I think my point there is that I don't think actual distribution "names" matter so much as what their intended purposes are for varying the "what" that is measured for this metric.
