Mithras at Fables of the Reconstruction has been crunching the numbers:
As of this moment, Iraq Body Count says that between 23,589 and 26,705 Iraqi civilians have died since the United States invaded Iraq. Let’s average that out, even though their method for counting deaths is extremely conservative and there is, I think, good reason to believe that the actual number of dead is higher than their high estimate. The average is 25,147.
The CIA World Factbook says that the population of Iraq as of July 2005 was 26,074,906. At the same time, the population of the United States was 295,734,134.
So, if someone invaded the United States and the same proportion of the civilian population had died as a result, the number of people killed would be 285,210.
Or think of it this way: on September 11, 2,986 people died. The equivalent of what has happened in Iraq is the equivalent of September 11th repeated 95 times.