The United States' partnership with the Netherlands is its oldest continuous relationship and dates back to the American Revolution. The Netherlands is a geographically small (approximately the size of the State of Maryland), densely populated (16.5 million people) country occupying a highly strategic commercial location, with Europe's largest Port, that makes it the "Gateway to Europe." Over 160 million consumers (roughly one third of the population of the expanded European Union of 27 Member States) reside within a 300-mile radius of Rotterdam. More than sixty percent of the Netherlands' GDP is generated by foreign trade in goods and services. The Netherlands is a key center within the global business network with an advanced infrastructure geared towards the transportation of goods, people, and electronic data. Its core distribution points include Rotterdam, Europe's largest port, and Amsterdam Schiphol Airport, the fourth largest in Europe. The Netherlands has capitalized on its location and advanced economy to become one of the top dozen trading countries in the world. It is currently ranked 16th in GDP in the world, eighth in imports of goods and services from the United States, and third in direct investment in the United States. The United States is the largest foreign investor in the Netherlands and has its largest bilateral trade surplus in the world with this country ($16 billion in 2010).