The United Kingdom is the only country as a EU member state to have held referendums on continued membership of the European Union and its antecedent organisation, the European Communities. In the first referendum in 1975, continued membership of what was then the European Communities (which included the European Economic Community, often referred to as the "Common Market" in the UK) was approved by 67.2% of voters, while in its second referendum in 2016 voters voted by 51.9% to leave the European Union.