Greece is classified as an advanced,[39] high-income economy,[40] and was a founding member of the Organisation for Economic Co-operation and Development (OECD) and the Organization of the Black Sea Economic Cooperation (BSEC). The Treaty of Accession of Greece to the European Communities was signed on 28 May 1979, and the country formally joined what is now the European Union on 1 January 1981.[3] On 1 January 2001 Greece adopted the euro as its currency, replacing the Greek drachma at an exchange rate of 340.75 drachmae per euro.[3][41] Greece is also a member of the International Monetary Fund and the World Trade Organization, and is ranked 31st on the KOF Globalization Index for 2010 and 34th on the Ernst & Young’s Globalization Index 2011.[42]