I agree that "a significant proportion" should not be interpreted as "most," and you make a good case for your percentage numbers. The refugee organizations also counted around two million refugees during the first Gulf War, and I don't know how many of those stayed and how many went back. I also don't know how much "turnover" there is. Some neighborhoods in Baghdad are filling up again, but so far, certainly not in numbers anywhere close to the numbers that left.

I'm not saying this isn't a problem. Just that accuracy would be nice. The refugees started pouring out of Iraq not when the U.S. invaded, but quite a while later, when the insurgents, terrorists, and secular gangs started killing Iraqis in large numbers.