This is a good primary source -- relevant example: 'Yearbook of Immigration Statistics 2016', Table 9 [1]. [1] https://www.dhs.gov/immigration-statistics/yearb

This is a good primary source -- relevant example: 'Yearbook of Immigration Statistics 2016', Table 9 [1]. [1] https://www.dhs.gov/immigration-statistics/yearbook/2016/table9 https://www.dhs.gov/immigration-statistics/yearbook/2016/tab...