The krone is Norway's official currency, with banknotes ranging from 50 to 1000 kroner, and coins in 1, 5, 10, and 20 kroner. There is also a smaller coin, the øre, worth 50 øre to 1 krone. Introduced in 1875, the krone replaced the rigsdaler at an exchange rate of 4 kroner = 1 rigsdaler. Norway joined the Scandinavian Monetary Union, and until 1914, all Scandinavian countries used the same currency. Norwegian krone coins are similar to coins from other countries, like the Syrian pound, causing confusion in coin-operated machines. The krone's value fluctuates mainly due to oil prices, reaching a record high in 2002 when oil prices also peaked.