The percentage of the 25M Iraqis that are fighting back, and the percentage that were recruited and trained by US troops. Also the allied troops in this war. Plus Iraq had no decent radar for flying at night, and no IR goggles, so US Troops have an advantage at night. No wonder Saddam ended up in a Spider-Hole.
The big question, is if it takes 12 months to train a US Trooper from Basic to Advanced Training to be battle-ready, how come it is taking so long to train Iraqi troops? They apparently only have 100,000 Iraqi troops, police, and security guards and they need 100,000 more to make it 200,000. Out of 18 Territories in Iraq, only 3 are being attacked by terrorists and rebels.
I feel the need to cite the song "Should I stay or should I go now?" by "The Clash" right about now that the election is less than two months away. :)