Between 2002 and 2023, prices of OPEC Reference Basket oils fluctuated dramatically. For example, Saharan Blend from Algeria stood at some 25 U.S. dollars per barrel in 2002. Ten years later, this figure had increased to more than 111 U.S. dollars. In 2023, it stood at 83.64 U.S. dollars. Oil prices: a rollercoaster ride Oil prices are inherently volatile due to the speculative nature of their price determination. Thus, sudden economic and geopolitical events may have big influences on pricing. For example, some of the major factors behind price fluctuation since the 2000s have been the global financial crisis in 2008, the 2020 coronavirus pandemic, and the energy supply crisis and subsequent Russia-Ukraine war in 2022. As a result, the OPEC crude oil price have oscillated between lows of 40 U.S. dollars and highs of 110 U.S. dollars. Shale oil overproduction leads to 2010 oil glut The 2010s price crash was caused in part by ever-growing production of domestic shale and tight oil in the United States. Though nearly 80 percent of global oil reserves can be found in OPEC countries, the United States has become the largest producer of oil worldwide in the last ten years.