See attached plot of National Debt as percentage of GDP.
Some data is shifted by up to 6 months, but I think the overall trend is still indicative. Of course, the really big debts are the "off budget" ones, like SS and Medicaid.
From data on these web sites, by simple division:
http://www.publicdebt.treas.gov/opd/opd.htm#history
Louis D. Johnston and Samuel H. Williamson, "The Annual Real and Nominal GDP for the United States, 1790 - Present." Economic History Services, October 2005, URL : http://www.eh.net/hmit/gdp/
(Attachment debt.gif is missing)
Richard, for reason with my off brand
browser on high magnification I can't
see any graphs, but I will guess that
the government graph flattens debt v
gdp. and like you said this doesn't
account for off budget debt, and maybe
doesn't account for deducting social
security nominal excess revenue
against current debt even that revenue
is needed to marginally offset future
social security liabilities. Also the
current revenues are enlarged by
capital gains taxes on the bond bubble,
the housing bubble, the stock echo
bubble, inflation driving more middle
class people into the alternative
minimum tax, and of course the
government collects and massages the
statistics that go into the gdp. Of course
if the government were held to
Sarbanes Oxley acccounting rules with
President forced to sign along with the
sec of the treasury, under penalty of
impeachment and conviction, then
maybe the figure would approach the
truth. Then we have the corporate debt,
the state debt, teh local debt, and the
individual debt.