The current drunken sailor in chief has presided over inflating that number back up to about 20.5% for this year including Katrina spending.
My source was the Wall Street Journal for the figures I cited. I guess I can't dispute the link you sent though I didn't bother to read it since it was just way too much information to deal with right now. I have no reason to disbelieve the Journal's figures however, and the 21.6% I cited was actually a figure from 1998 and 1999, not 1994. They also recently cited the 17% figure for current spending levels.
Anyway, I don't know what to make of the disparity. Maybe I, you or us are misinterepreting something in the data we saw. Perhaps later if I have time I will sort through that PDF file you linked to in order to make heads or tails of it.
However, if spending went down as a percent of GNP under Clinton, it wasn't through spending discipline, that's for sure. It was through the rise of the GNP that the relative portion of spending went down.