The US has been first, and Germany has been second in the number of immigrants it receives. Other countries, especially three in the Persian Gulf, have populations with enormous percentages of immigrants.
The diagram below provides a comprehensive overview. Looking at migrants since the 2000s, we can see a steep increase since 1970, when the difficult ethnic quotas per country were abolished. Dr. Martin offers staggering examples resulting from US immigration policies. The greatest migrations were in the 1900s and 1910s.
Dr. Martin also heads the LWV Immigration Committee. She notes that Washington State has various studies on migrants, so good data can be found there.
Susan Martin invited speaker on immigration: LWV of WA