The EU customs union has become the world’s largest trading bloc. In 2015, the EU accounted for some 15 % of world trade in goods, worth €3.5 trillion (€1.73 trillion in imports and €1.79 trillion in exports). The main EU trade partners are the United States, China, Switzerland, Russia and Turkey. The EU is the only customs union which is itself a member of the World Trade Organization (WTO). At the same time, the EU is a signatory to 30 free trade areas and 3 customs unions, with 56 partners that are WTO members or observers. These 33 arrangements cover about one third of EU trade.