import growth led to the large trade surpluses that emerged in the 1980s. In general, Japan has not imported an unusually large amount as a share of its GNP, but it has been highly dependent on imports for a variety of critical raw materials. Japan has by no means been the only industrialized nation dependent on imported raw materials, but it has depended on imports for a wider variety of materials, and often for a higher share of its needs for these materials. The country imported, for example, 50% of its caloric intake of food and about 30% of the total value of food consumed in the late 1980s. It also depended on imports for about 85% of its total energy needs (including all of its petroleum and 89% of its coal) and nearly all of its iron, copper, lead, and nickel. The long-term growth in imports was facilitated by several major factors. The most important was general growth in the Japanese economy and income levels. Rising real incomes increased demand for imports, both those consumed directly and those entering into production. Another factor was the shift in the economy toward greater reliance on imported raw materials. Primary energy sources in the late 1940s, for example, were domestic coal and charcoal. The shift to imported oil and coal as major energy sources did not come until the late 1950s and 1960s. The small size and poor quality of many of the mineral deposits in Japan, combined with innovations in ocean transportation, such as bulk ore carriers, meant that as the economy grew, demand outstripped domestic supply and cheaper imports were utilized. The price of imports was also a factor in their growth. In 1973 Japan's import price index was at essentially the same level as in 1955, partly because of the appreciation of the yen after 1971, which reduced the yen price of imports, but also because of the reduced costs of ocean shipping and stable prices for food and raw materials. For the rest of the 1970s, however, import prices skyrocketed, climbing 219% from 1973 to 1980. This dramatic price rise, especially for petroleum but by no means confined to it, was responsible for the rapid growth of the dollar value of imports during the 1970s, despite the slower growth of the economy. During the 1980s, import prices fell again, especially for petroleum, dropping by 44% from 1980 to