Statistics refer to international migrant stocks. Stocks include all foreign-born residents in a country regardless of when they entered the country. For countries where data on the foreign-born population are not available, UNDESA uses data on foreign citizens. As such, the number of international migrants may not include second-generation migrants that were born in the country but have parents who migrated. Stock data should also not be confused with annual migration flow data (i.e. the number of migrants that entered or left a country within one year).