the Gulf Coast, has become the most significant trading hub for crude oil in North America. In Europe and some other parts of the world, the price of the oil benchmark is Brent Crude as traded on the Intercontinental Exchange (ICE, into which the International Petroleum Exchange has been incorporated) for delivery at Sullom Voe. Brent oil is produced in coastal waters (North Sea) of UK and Norway. The total consumption of crude oil in UK and Norway is more than the oil production in these countries. So Brent crude market is very opaque with very low oil trade physically. Brent price is used widely to fix the prices of crude oil, LPG, LNG, natural gas, etc. trade globally including Middle East crude oils. There is a differential in the price of a barrel of oil based on its grade—determined by factors such as its specific gravity or API gravity and its sulfur content—and its location—for example, its proximity to tidewater and refineries. Heavier, sour crude oils lacking in tidewater access—such as Western Canadian Select—are less expensive than lighter, sweeter oil—such as WTI. The Energy Information Administration (EIA) uses the imported refiner acquisition cost, the weighted average cost of all oil imported into the US, as its "world oil price". Global oil prices: a chronology The price of oil remained "relatively consistent" from 1861 until the 1970s. In Daniel Yergin's 1991 Pulitzer prize-winning book The Prize: The Epic Quest for Oil, Money, and Power, Yergin described how the "oil-supply management system"—which had been run by "international oil companies"—had "crumbled" in 1973. Yergin states that the role of Organization of the Petroleum Exporting Countries (OPEC)—which had been established in 1960, by Iran, Iraq, Kuwait, Saudi Arabia and Venezuela— in controlling the price of oil, was dramatically changed. Since 1927, a cartel known as the "Seven Sisters"—five of which were headquartered in the United States—had been controlling posted prices since the so-called 1927 Red Line Agreement and 1928 Achnacarry Agreement, and had achieved a high level of price stability until 1972, according to Yergin. There were two major energy crisis in the 1970s: the 1973 oil crisis and the 1979 energy crisis that affected the price of oil. Starting in the early 1970s—when domestic production of oil was insufficient to satisfy increasing domestic demands—the US had become increasingly dependent on oil imports from the Middle East. Until the early 1970s, the price