http://en.wikipedia.org/wiki/Demographics_of_the_Netherlands#Genetics
Looks like 80% "white" or ethnic Dutch.
http://en.wikipedia.org/wiki/Demographics_of_France
It's currently illegal to count people by ethnicity in France, so hard to say for sure. However:
"Solis, a marketing company, recently estimated the numbers for ethnic minorities (immigrants and 2nd generation) in France in 2009 as 3.26 million Maghrebis (5.23%), 1.83 million Black people (2.94%, 1.08 million Sub-Saharan Africans and 757,000 French from French West Indies) and 441,000 Turkish (0.71%)
."
http://en.wikipedia.org/wiki/Demographics_of_the_United_States
Looks like 72% "white", but of this, the US counts persons of Hispanic origin differently. Consider also that that 72% is not monolithic (e.g., there are persons that are Dutch, German, English, Nordic, etc.) rather than solely one ethnic origin. The US doesn't even try to count people of different "white" origins in census data.
Yes--immigration has become more of an issue in the last 50 or so years for Europe. Your point may stand, but it is on very shaky ground since pretty much 80+ percent of Holland or France appears to be of one origin. Perhaps one could be informed by a population and a continent that has been dealing with immigration issues a little longer? I think the Americas have been dealing with the issue for about 520 years.