97. Massive exports have supported China's fast expansion since the 1980s. A considerable portion of these exports are destined for the United States, which in 2012 surpassed the European Union as China's top export market. Until July of this year, China was the United States' second-largest commercial partner, third-largest export market, and by far its greatest source of imports. The massive expansion of economic relations between the United States and China, which accelerated with China's admission to the World Commerce Organization in 2001, is reflected in a more than 100-fold increase in overall trade between the two countries, from $5 billion in 1981 to $559 billion in 2013. why china is manipulating its currency ? answer briefly