Five primary energy consumer classes, namely Super, Major, Big, Medium and Small, are proposed, depending on the polymodal characteristics of the frequency distribution curve of their share of the total. The total primary energy consumption and its annual additions decrease, whereas the rates increase steadily from the Super to the Medium consumers. Since the frequency distribution histogram of additional primary energy consumptions of the Medium and above consumers during 1980-1999 is a typical bell shaped curve, the additional amounts and rates are used together to evaluate the performance levels of the countries in both parameters. The most successful countries are the USA, China, South Korea, Thailand, India, Indonesia, Taiwan, Turkey and Iran. The reason why the Super consumer USA and the Major consumer China are the biggest energy markets is because they are the first two biggest economies in the world. The success of the developing Asian countries is mostly related to their economic ties with the Super consumer USA. Among the other emerging markets, Turkey's primary energy demand has grown more rapidly than that of Iran and is expected to continue growing in the future. The emerging Medium and Big consumer markets will continue to play a significant role in the world's energy sector during the first two decades of the 21st century. (C) 2003 Elsevier Ltd. All rights reserved.