Baptized on Credit
Once again I go direct from your post to FRED. The FEDFUNDS peak falls between the 1980 and '82 recessions. So rates were falling for almost all of the high-spot on your graph. I think this fits with your note on "treasury duration".Some similarity to Federal surplus and deficit, as well.I do not understand your note below the graph.
Art,I do not know if the data correspond to intra-governmental debt.