Immigration research...

Immigration numbers - http://www.dhs.gov/ximgtn/statistics/publications/yearbook.shtm

Good papers at http://hbswk.hbs.edu/item/5761.html

Ethnic composition of US inventors - http://www.hbs.edu/research/pdf/08-006.pdf

Chinese - 8%

Europeans - 6.5%

Indians - 5%