They're responsible for a very large chunk of them, and many of them inexcusable war crimes. Looking into it now (sporadically, since I'm at work, which is why this post is taking a while) the first two years of the war in Iraq were the deadliest for civilians, and
coalition troops were directly responsible for the largest portion.
The IBC project released a report detailing the deaths it recorded between March 2003 and March 2005[88] in which it recorded 24,865 civilian deaths. The report says the U.S. and its allies were responsible for the largest share (37%) of the 24,865 deaths.
The second largest portion (36%) was crime, which is presumably a result of de-stabilization caused by the war.
Civilian deaths as a direct result of coalition violence fell off after that, but still remains a very large chunk.
According to one of the more recent long-term analysis by the IBC project.
14,925 (13%) of all documented civilian deaths were reported as being directly caused by the US-led coalition.
And when compared to the body count of those officially classified as enemies, 24,000 who also weren't all killed by coalition forces, that's still a pretty miserable number.
Keep in mind that the IBC project's methodology is complete reliance on data compiled from western media reports and the military's own leaked records, which has been heavily criticized as providing the lowest possible estimates. Testimonies from soldiers especially indicate that there was a lot of killing of civilians that was undocumented or framed as insurgent violence (such as the regular use of "drop weapons").
But more importantly that even if U.S. forces didn't directly carry out all of the killing of civilians, that doesn't change how what they did do reflects on them, or the fact that all of it was the result of their unprovoked initiation of war. At this point, I'm not even sure what you're trying to accomplish. If you're trying to say that the U.S. hasn't been responsible for a long list of egregious war crimes, or if it's ok just because not everything bad can be pinned on them.