Nearly 80 percent of Mexico’s exports in 2013 went to the United States. In 2013, Mexico was the third-largest supplier of foreign crude oil to the United States, as well as the largest export market for U.S. refined petroleum products and a growing market for U.S. natural gas.early 80 percent of Mexico’s exports in 2013 went to the United States. In 2013, Mexico was the third-largest supplier of foreign crude oil to the United States, as well as the largest export market for U.S. refined petroleum products and a growing market for U.S. natural gas.