Consider the United States and the countries it trades with the most (measured in trade volume): Canada, Mexico, China, and Japan. For simplicity, assume these are the only four countries with which the United States trades. Trade shares and exchange rates for these four countries are as follows:

Country (currency) Share of trade $ per FX in 2009 Dollar per FX in 2010 Canada (dollar) 36% 0.9225 0.9643 Mexico (peso) 28% 0.0756 0.0788 China (yuan) 20% 0.1464 0.1473 Japan (yen) 16% 0.0105 0.0112