The United States is the world's largest national economy in nominal terms, representing 22% of nominal global GDP and 17% of global GDP (PPP).[2] The United States' GDP was estimated to be $17.914 trillion as of Q2 2015.[2][30] The U.S. dollar is the currency most used in international transactions and is the world's foremost reserve currency.[31] Several countries use it as their official currency, and in many others it is the de facto currency.[32] The United States has a mixed economy[33][34] and has maintained a stable overall GDP growth rate, a moderate unemployment rate, and high levels of research and capital investment.[35] Its seven largest trading partners are Canada, China, Mexico, Japan, Germany, South Korea, and the United Kingdom.[36]
