Economy

The United States has a capitalist mixed economy, which is fueled by abundant natural resources, a well-developed infrastructure, and high productivity.[161] According to the International Monetary Fund, the U.S. GDP of $15.1 trillion constitutes 22% of the gross world product at market exchange rates and over 19% of the gross world product at purchasing power parity (PPP).[3] Though larger than any other nation's, its national GDP was about 5% smaller at
PPP in 2011 than the European Union's, whose population is around 62% higher.[162] The country ranks ninth in the world in nominal GDP per capita and sixth in GDP per capita at PPP.[3] The U.S. dollar is the world's primary reserve currency.[163]
The United States is the largest importer of goods and second largest exporter, though exports per capita are relatively low. In 2010, the total U.S. trade deficit was $635 billion.[164] Canada, China, Mexico, Japan, and Germany are its top trading partners.[165] In 2010, oil was the largest import commodity, while transportation equipment was the country's largest export.[164] China is the largest foreign holder of U.S. public debt.[166]