The Organisation of Petroleum Exporting Countries (OPEC), is a cartel of 12 countries made up of Algeria, Angola, Ecuador, Iran, Iraq, Kuwait, Libya, Nigeria, Qatar, Saudi Arabia, the United Arab Emirates, and Venezuela. The Economist produced this great graphic as the cartel of oil producers, celebrated its 50th anniversary on September 14th. The organisation was founded in 1960 with the clear motive of influencing oil prices by controlling supplies. It has generally proved successful. OPEC controls around 80% of the world’s proven reserves and over 40% of the world’s production among its 12 member states. The Gulf states that dominate OPEC have the biggest reserves and lowest costs, so can most easily turn the taps on and off when required to keep prices high. Despite the slow return to health of a sickly world economy, oil fetches a lofty $75 a barrel, which Saudi Arabia, OPEC’s most influential member reckons is “ideal”.