How many soldiers have been sent to Iraq?

According to The BBC, the United States sent about 100,000 to 150,000 ground troops to Iraq between 2003 and 2009. These figures don't include the surge in numbers that occurred in 2007.

Following the election of Barack Obama, ground troops were scaled back at a faster rate, and the last combat brigade left in August 2010. Up to that point, 4,421 troops had been killed and almost 32,000 had been wounded in action. About 50,000 military personnel remained in Iraq to aid in the transition process. In contrast, the British army had lower levels of troops deployed, hitting a peak in 2003 at 18,000.