Washington has a growing, diversified economy with an increasing percentage of professional and business service jobs. The gross product of the Washington Metropolitan Area makes it the fourth-largest metropolitan economy in the United States. The federal government accounted for about 29% of the jobs in Washington, D.C. This is thought to immunize Washington to national economic downturns because the federal government continues operations even during recessions. Many organizations such as law firms, independent contractors (both defense and civilian), non-profit organizations, lobbying firms, trade unions, industry trade groups, and professional associations have their headquarters in or near D.C. to be close to the federal government. Tourism is Washington’s second largest industry. Approximately 18.9 million visitors contributes to the local economy every year. The District also hosts nearly 200 foreign embassies and international organizations such as the World Bank, the International Monetary Fund (IMF), the Organization of American States, the Inter-American Development Bank, and the Pan American Health Organization. The District has growing industries not directly related to government, especially in the areas of education, finance, public policy, and scientific research. Georgetown University, George Washington University, Washington Hospital Center, Children’s National Medical Center and Howard University are the top five non-government-related employers in the city. Four of the largest 500 companies in the country are also headquartered in the District.