Also, it seemed to me a normalized view of the debt structure would be informative. Here is the percentage of the Treasury marketable debt for each component over the time series. Again, interesting trends emerge - the relative proportion of T Bills was falling in the October report 2002-2007 s total debt was steadily climbing - until 2008, with an explosion of short term debt.
(NB: The Treasury debt under consideration is the Marketable category, which the debt held by the public, other CB's etc. Hat tip to PeakVT for pointing that out. Also, some graph improvements done for today's post courtesy of Mel and Comrade Counterpointer's suggestion.)
(Addendum: MLM clarification - we are at a tipping point, some external event is needed to trigger the change from a 'status quo' approach to rollover in the Treasury market - then lookout.)