Reserve currency before the beginning of the worldwide credit crunch related recession and Eurozone crisis, which harmed the euro and slowed its adoption. Since 2009, the reserve currency use of the euro has continued to drop, down to 23.9 percent in 2013. The Dutch guilder was the "de facto" reserve currency in Europe in 17th and 18th centuries. The United Kingdom's pound sterling was the primary reserve currency of much of the world in the 19th century and first half of the 20th century. The emergence of the USA as an economic superpower, and the establishment of the U.S. Federal Reserve System
Currency War of 2009–11 dollar float freely. While the US has taken no direct action to devalue its currency, there is close to universal consensus among analysts that its quantitative easing programmes exert downwards pressure on the dollar. According to many analysts the currency war had largely fizzled out by mid-2011, though others including Mantega disagreed. As of March 2012, outbreaks of rhetoric were still occurring, with additional measures being adopted by countries like Brazil to control the appreciation of their currency. Yet by June, there were signs that currency misalignment had been levelling out in China and across the world, with even Mantega