Vatican City issues its own coins and stamps. It has used the euro as its currency since 1 January 1999, owing to a special agreement with the European Union (council decision 1999/98). Euro coins and notes were introduced on 1 January 2002—the Vatican does not issue euro banknotes. Issuance of euro-denominated coins is strictly limited by treaty, though somewhat more than usual is allowed in a year in which there is a change in the papacy. Because of their rarity, Vatican euro coins are highly sought by collectors. Until the adoption of the Euro, Vatican coinage and stamps were denominated in their own Vatican lira currency, which was on par with the Italian lira.