It is impossible to fairly rank and compare countries. Look at the populations of the countries on that first list that are ranked above the US:
- Switzerland - 8.5M
- Japan - 126.8M
- Canada - 36.7M
- Germany - 82.7M
- UK - 66.0M
- Sweden - 10.1M
- Australia - 24.6M
- US - 325.7M
The US population is almost as large as the combined populations of the 7 countries ranked above it on this list. And on top of the sheer size difference in the populations, the population diversity is not remotely comparable.
One in 7 US residents is foreign born, which means the US has more foreign born residents than 4 of the countries ranked above it in this list.
I also looked at the ranking methodology, and it is unclear... it appears that the US should rank above the UK on their list, which would put the US at #7.