The Euro is the official currency of the European Union (EU) and the only currency of the 16 member countries of the Economic and Monetary Union: Austria, Belgium, Cyprus, Finland, Greece, Ireland, Italy, Luxembourg, Malta, Netherlands, Portugal, Slovakia, Slovenia and Spain. Informally known as the Eurozone, with a population of over 320 million inhabitants to which can be added the other countries with currencies tied to the Euro, totalling 480 million people directly involved with the Euro. Eleven of the 27 member states of the European Union have not adopted the Euro as their official currency, for instance: Denmark and United Kingdom benefit from an exemption clause that allows them to keep their national currencies indefinitely; even Sweden, part of the EU since 1995, continues to use its Krona. The remaining eight member countries await compliance with the macroeconomic requirements of the Maastricht Treaty before fully joining the Euro. In addition to EU members there are the micro-states of the Vatican city, the Principality of Monaco, San Marino and Andorra, which have adopted the Euro by virtue of the pre-existing agreements with neighbouring countries (in fact Andorra does not strike Euro coins). Finally, Montenegro and the independent Republic of Kosovo have unilaterally adopted the Euro. The Euro's debut on the financial markets was in 1999, but actual the coins and notes went into the circulation on 1st January 2002 in the twelve countries that first adopted the new currency.