The Russian Federation has the second largest number of foreign-born persons residing on its territory, after the United States. Most in- and out-migration is with other countries of the former Soviet Union (FSU). According to the 2002 Census, the most recent data available on the immigrant population, there were 12 million foreign-born persons in the Russian Federation in that year, about 8.3% of the total population. Close to 90% were of Russian nationality and indeed, most were from the FSU, whose break-up transformed overnight many persons born in these republics into foreign-born persons. Some 3.5 million were from Ukraine and a further 2.5 million from Kazakhstan.