This shows the largest percentage irrespective of population, which skews the figures quite a bit, since statistical anomalies easily get propelled to the top spot. For example, I'm pretty sure there are more Nigerians in New York City than the site's pick of "Fort Bend County, Texas", and I wouldn't be surprised if the nation's apparent #1 Belgian community in Weber, UT (which seems to be flying under the radar as far as Google is concerned) was a single large Mormon family.