At $73.6 billion in 2004, U.S.-Canada trade in energy is the largest U.S. energy trading relationship, with the overwhelming majority ($66.7 billion) being exports from Canada. The primary components of U.S. energy trade with Canada are petroleum, natural gas, and electricity. Canada is the United States' largest oil supplier and the fifth-largest energy producing country in the world. Canada provides about 16% of U.S. oil imports and 14% of total U.S. consumption of natural gas. The United States and Canada's national electricity grids are linked, and both countries share hydropower facilities on the western borders.