But the World Tourism Organization predicts that China will become the world's fourth-largest source of overseas tourists by 2020.

The U.S. enjoys a strong exporter position with Lebanon, generally ranking as Lebanon's fourth-largest source of imported goods.

Together, the estate tax credit and the transfer inheritance tax make up the fourth-largest source of tax revenue in New Jersey.

In addition, almost overnight it has become the world's fourth-largest source of opium poppies, the raw material for heroin.

For Nigeria, the fourth-largest foreign source of crude oil for the United States last year, diversification follows economic desperation.

Long a cocaine refining country, Colombia emerged in the 1990's as the world's third-largest source of cocoa leaves and the fourth-largest source of opium.

Nuclear power is the fourth-largest source of electricity in India after thermal, hydroelectric and renewable sources of electricity.

By 2004, Japan had become Bangladesh's fourth-largest source of foreign direct investment, behind the United States, United Kingdom, and Malaysia.

Corporation tax forms the fourth-largest source of government revenue (after income, NIC, and VAT).

Venezuela has been the fourth-largest source of oil for the United States, behind Saudi Arabia, Mexico and Canada, providing 14 percent of the nation's crude oil imports.