2001 President George Bush came into office inheriting a surplus from President Bill Clinton. The CBO projected in the 10 years from 2001-2011 the total surplus would be 5.6 trillion dollars and the national debt would be paid off by 2011, this assumed that revenue remained the same and spending didn't increase higher than inflation.
So why did President Bush leave office with a 10 trillion dollar debt instead of the projected surplus? First came government spending which increased over 5.6 trillion dollars, this on top of a huge tax cut that removed 6.1 trillion in revenue coming into the government.
When you factor in the debt almost everyone ignores the surplus that was left, if he had just kept taxes and spending at the same level President Bush would have left office with no national debt instead of the 10.6 trillion he left.
So if you want to be honest President Bush is responsible for all debt when President Obama took office, instead of inheriting a balanced budget and a surplus.
Now factor in the yearly deficit that President Bush left President Obama of 500 billion dollars a year and the debt if Obama hadn't increased spending 1 penny would be at 13 trillion dollars all due to President Bush's policies.
Now the debt is 18 trillion so President Obama has increased spending and added 5 trillion to the debt but far less than the 13 trillion Bush added and actually this years deficit as a percentage of GDP is lower than 2008.