Central and Eastern Europe Soviet Union; the independent states in former Yugoslavia (which were not considered part of the Eastern bloc); and the three Baltic states – Estonia, Latvia, Lithuania (which chose not to join the CIS with the other 12 former republics of the USSR). The CEE countries are further subdivided by their accession status to the European Union (EU): the eight first-wave accession countries that joined the EU on 1 May 2004 (Estonia, Latvia, Lithuania, Czech Republic, Slovakia, Poland, Hungary, and Slovenia), the two second-wave accession countries that joined on 1 January 2007 (Romania and Bulgaria) and the third-wave accession country that
European Union Slovenia joined the Union. In 2007, Bulgaria and Romania became EU members. The same year, Slovenia adopted the euro, followed in 2008 by Cyprus and Malta, by Slovakia in 2009, by Estonia in 2011, by Latvia in 2014, and by Lithuania in 2015. On 1 December 2009, the Lisbon Treaty entered into force and reformed many aspects of the EU. In particular, it changed the legal structure of the European Union, merging the EU three pillars system into a single legal entity provisioned with a legal personality, created a permanent President of the European Council, the first of which was