The Nikkei International Commodity Index is comprised of major international commodities such as energy and agricultural products. The index is calculated based on the commodity prices in US dollar of 14 items e.g. naphtha as a petroleum product, copper as a nonferrous metal and wheat as an agricultural product, weighted by the amounts of imports of the developed countries. It has been published since April 1985. The index measures comprehensive fluctuation of international commodity prices and has been utilized as a leading indicator for global economic trends.