It is true that over the same period the debt has been reduced, interest rates have come down. To throw out a number to put that in context, in 1996 debt charges represented roughly 30% of revenues; they're down to something like 14%. Now that we're in an era of lower interest rates, it would be natural that the reduction in that ratio would taper off somewhat.
On November 20th, 2007. See this statement in context.