My point is that to me, and perhaps to many who don't live in the USA, the entire question feels USA-centric. There's a significant difference between being a first generation Bulgaria->Sweden immigrant and being a first generation Germany->Netherlands immigrant. It's just fundamentally different, and I think a poll like this demonstrates a non-understanding of that.
The thinking in the USA seems to be that either you're an immigrant or you're not, with no distinction between the variation of cultures. To a western European this kind of thinking seems very parochial.
The very idea of asking this kind of question makes it seems USA-centric, because the USA has such a strong self-identification as the land of opportunity for immigrants. The discussions about H1-B visas indicates the schizoid nature of that identity.
I've heard it said that the difference between Britain and the USA is that the British think 100 miles is a long way, while Americans think 100 years is a long time.
Again, all of this is my impression, but you did ask.