The Swedish krona is the official currency of Sweden, introduced in 1873. One krona is divided into 100 öre, though öre coins ceased to be valid in 2010. The Swedish krona is one of the top 10 most popular currencies worldwide. The krona replaced the riksdaler in 1876 and was used by Denmark, Sweden, and Norway until World War I. After the countries separated, each continued using kronas with national symbols. The current series of Swedish coins was introduced in 2012, featuring a new design and reintroducing the two-krona coin. The krona was weakest in 2009 but became the strongest in 2012, matching the Euro, due to the Greek financial crisis. Despite an agreement for Sweden to adopt the euro after joining the Eurozone in 1994, a 2003 referendum resulted in most voters rejecting the euro, and Sweden continues to use the krona.