I have talked to a number of people who participated in Operation Desert Storm, as well as read a good number of books on the subject. 45% of our casualties were caused by our own troops killing each other. A major cause of death was being run over by military vehicles.
According to some individuals I know who shall remain nameless upon condition of anonymity, reported deaths related to our troops in Iraq have a qualification. If the person died in Iraq then they are considered a causality. If a person is wounded and receives medical treatment outside of Iraq (Germany is popular) and that person dies, they are not a causality of the War Against Terror.