Since the 1970s there have been more people seeking to emigrate to richer countries than the latter have been willing to admit, either temporarily or permanently. In recent years, international migration has been increasing at an unprecedented level. Currently, some 80 to 100 million immigrants, refugees, or asylum-seekers and migrant workers are outside their country of citizenship. Since most recipient countries do not desire further significant numbers of immigrants, one method advocated to relieve the pressures of international migration is to make more overseas development aid (ODA) available to improve living standards (thus incentives to stay) in those countries with high emigration rates. ODA is one of four primary means through which industrialized countries individually and collectively influence economic and political developments in emigrating countries. However, there is agreement that only ODA is under the direct control of industrialized country governments, and ODA can therefore theoretically be tailored to influence emigration pressures in other nations.