Estonian kroon until the Soviet invasion in 1940 and Estonia's subsequent incorporation into the Soviet Union when it was replaced by the Soviet ruble. After Estonia regained its independence, the kroon was reintroduced in 1992. The kroon became the currency of Estonia on 1 September 1928 after having been a unit of account since 1924. It replaced the mark at a rate of 100 mark = 1 kroon. The kroon was subdivided into 100 sent. In 1924, the kroon was pegged to the Swedish krona at par, with a gold standard of 2480 kroon = 1 kilogram of pure gold. The standard
Economic and Monetary Union of the European Union eurozone member states and to impose flexible labour markets and flexible wages, might constitute a serious threat to Social Europe. In December 2012, at the height of the European sovereign debt crisis, which revealed a number of weaknesses in the architecture of the EMU, a report entitled ""Towards a genuine Economic and Monetary Union"" was issued by the four presidents of the Council, European Commission, ECB and Eurogroup. The report outlined the following roadmap for implementing actions being required to ensure the stability and integrity of the EMU: In June 2015, a follow-up report entitled ""Completing Europe's Economic and Monetary