What areas have been the main sources of immigrations in recent years?

Other regions accounting for significant shares were Europe and Canada (13.5 percent), the Caribbean (9.6 percent), Central America (7.9 percent), South America (6.7 percent), the Middle East (4 percent) and sub-Saharan Africa (3.9 percent).

Explanation:

newly independent countries of the former ussr

because it took place after the war of 1812 had come to an end.