Throughout this article, the unqualified term “dollar” and the $ symbol refer to the US dollar. The United States is the world’s largest national economy, representing 22% of nominal global GDP and 17% of global GDP (PPP). The United States’ GDP was estimated to be $17.711 trillion as of Q4 2014. The U.S. dollar is the currency most used in international transactions and is the world’s foremost reserve currency. Several countries use it as their official currency, and in many others it is the de facto currency. The United States has a mixed economy and has maintained a stable overall GDP growth rate, a moderate unemployment rate, and high levels of research and capital investment. Its six largest trading partners are Canada, China, Mexico, Japan, Germany, and South Korea. The US has abundant natural resources, a well-developed infrastructure, and high productivity. It has the world’s ninth-highest per capita GDP (nominal) and tenth-highest per capita GDP (PPP) as of 2013. Americans have the highest average household and employee income among OECD nations, and in 2010 had the fourth highest median household income, down from second highest in 2007. It has been the world’s largest national economy (not including colonial empires) since at least the 1890s. The U.S. is the world’s largest producer of oil and natural gas. It is the second-largest trading nation in the world as well as the world’s second largest manufacturer, representing a fifth of the global manufacturing output. Of the world’s 500 largest companies, 128 are headquartered in the US. The United States has one of the world’s largest and most influential financial markets. The New York Stock Exchange is by far the world’s largest stock exchange by market capitalization. Foreign investments made in the US total almost $2.4 trillion, while American investments in foreign countries total over $3.3 trillion. Consumer spending comprises 71% of the US economy in 2013. The United States has the largest consumer market in the world, with a household final consumption expenditure five times larger than Japan’s. The labor market has attracted immigrants from all over the world and its net migration rate is among the highest in the world. The U.S. is one of the top-performing economies in studies such as the Ease of Doing Business Index, the Global Competitiveness Report, and others. The US economy is currently embroiled in the economic downturn which followed the financial crisis of 2007–08, with output still below potential according to the Congressional Budget Office. The economy, however, began to recover in the second half of 2009, and as of October 2014, unemployment had declined from a high of 10% to 5.8%; the government’s broader U-6 unemployment rate, which includes the part-time underemployed, was 11.8%. At 11.3%, the U.S. has one of the lowest labor union participation rates in the OECD. Households living on less than $2 per day before government benefits, doubled from 1996 levels to 1.5 million households in 2011, including 2.8 million children. The gap in income between rich and poor is greater in the United States than in any other developed country. Total public and private debt was $50 trillion at the end of the first quarter of 2010, or 3.5 times GDP. In December 2013, the total of the public debt was about 0.7 times GDP. Domestic financial assets totaled $131 trillion and domestic financial liabilities totaled $106 trillion.