G.W. Bush took control of the budget on Oct. 1, 2001, when the debt was $5.8 Trillion and his last budget year ended Oct. 1, 2009, with the debt at $11.9 Trillion. During that last year, Obama got a stimulus bill passed, but that's the only significant change he was able to make in federal spending. Actually spending that money takes a while to only $36 Billion ($0.036 Trillion) contributed to Bush's deficits. So instead of raising the debt $6.10 Trillion, he only raised it $6.07 Trillion.

But, really, $2.4 Trillion of that was interest on the Reagan-Bush-I debt, so Bush II was only responsible for $3.7 Trillion, but now there's been a year of interest on his debt. So all told, as of September 30, 2010, Reagan and the Bushes were responsible for $12 Trillion of the national debt. About $0.2 Trillion is still left from WWII, and Obama has $1.25 Trillion that's his. Of course half of the is from the Bush-II tax cuts and most of the rest is because of the Great Recession.

If Reagan and the Bushes had not let the debt outrun GDP, the national debt would now be $9.2 Trillion lower. That's not much to ask since every other president from 1946 to 2009 actually held the debt to less than GDP growth.

To phrase the question most clearly: What would the debt be now if Reagan and the two Bushes had held the debt to a constant percent of GDP during their budget years?

If we answer that, it is a simple matter to subtract it from the actual debt, and find out how much debt was caused by their mishandling of federal budgets -- taxes and spending.

Reagan took office in Jan 1981, but Carter's last budget continued until Sept 30. Buy July, Reagan had passed his Fiscal-Year 1982 budget, which took effect on October 1, 1981. In the twelve years (covering Reagan and G.W.H. Bush) from FY'81 to FY'93 the dollar GDP increased by 115%.

If Reagan and GHW Bush had limited the dollar debt growth to that dollar GDP growth, the debt would have increased from $995 to $2,144 billion. But it actually increased to $4,351B, so the excess increase, for which we hold them responsible, was $2,207B. Of course Reagan claimed he would have the dollar debt going down, not up, by his forth year and thereafter.

Without the extra $2,207B in debt there would have been less interest paid. Paying this interest slowed Clinton's progress against the debt. So to find out how much lower the debt could have been, we must add this interest to the Reagan-Bush debt. That interest compounded annually and averaged 6.56%. It increased their debt to $3,668B.

Since the actual debt was $5767B at that time, subtracting the Reagan-Bush debt shows it would have been only $2,101 without their debt surges. That would have been only 20.4% of GDP.

Now, as with Reagan and GHW Bush we assume that GW Bush should have kept debt at the same percent (20.4%) of GDP -- remember, Clinton reduce it 10%.

During GW Bush's terms, dollar GDP increased on 39%, so he should have held the debt to a 39% increase. It is important to remember our question: What would the debt be now if ...? So we take what the debt would have been just before GW Bush, in FY 2001, and escalate it by 39%. The result is $2,926B.

But the actual debt at the end of GW Bush's last budget year was $11,876B. From that we must subtract Obama's stimulus spending before Sept. 30, 2001. That was $36B. So at that time the Reagan-Bushes debt was $8,914.

The interest rate on the debt since then has been 3.3%, so their debt has now (Sept. 30, 2010) grown to $9,206B.