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
World currency to the idea of a single world currency, some evidence suggests the world may evolve multiple global currencies that exchange on a singular market system. The rise of digital global currencies owned by privately held companies or groups such as Ven suggest that multiple global currencies may offer wider formats for trade as they gain strength and wider acceptance. Blockchain offers the possibility that a decentralized system that works with little human intervention could eliminate squabbling over who would administer the world central bank. Bitcoin is so far the closest candidate for a world decentralised currency. Some economists argue that