Officially established by the Treaty of Maastricht in 1993 upon the foundations of the pre-existing European Economic Community. Thus, 12 states are founding members, namely, Belgium, Denmark, France, Germany, Greece, Ireland, Italy, Luxembourg, the Netherlands, Portugal, Spain, and the United Kingdom. In 1995, Austria, Finland and Sweden entered the EU. Cyprus, the Czech Republic, Estonia, Hungary, Latvia, Lithuania, Malta, Poland, Slovakia, and Slovenia joined in 2004. Bulgaria and Romania joined in 2007. Croatia acceded in 2013. The United Kingdom withdrew in 2020 after 47 years of membership. Official candidate states include Albania, North Macedonia, Montenegro, Serbia and Turkey. Morocco's application was rejected by the EEC. Iceland and Switzerland have withdrawn their respective applications. Norway rejected membership in two referendums. The institutions of the European Union, its parliamentarians, judges, commissioners and secretariat, the governments of its member states as well as their people, all play a role in European Integration. Nevertheless, the question of who plays the key role is disputed as there are different theories on European Integration focusing on different actors and agency. The European Union has a number of relationships with nations that are not formally part of the Union. According to the European Union's official site, and a statement by Commissioner Günter Verheugen, the aim is to have a ring of countries, sharing EU's democratic ideals and joining them in further integration without necessarily becoming full member states. Whilst most responsibilities ('competences') are retained by the member states, some competences are conferred exclusively on the Union for collective decision, some are shared pending Union action and some receive Union support. These are shown on this table: The European Union operates a single economic market across the territory of all its members, and uses a single currency between the Eurozone members. Further, the EU has a number of economic relationships with nations that are not formally part of the Union through the European Economic Area and customs union agreements. The creation of the EEC eliminated tariffs, quotas and preferences on goods among member states, which are the requisites to define a free trade area (FTA). The United Kingdom remains part of the FTA during the transition period of the Brexit withdrawal agreement. Numerous countries have signed a European Union Association Agreement (AA) with FTA provisions. These mainly include Mediterranean countries (Algeria in 2005, Egypt in 2004, Israel in 2000, Jordan in 2002, Lebanon in 2006, Morocco in 2000, Palestinian National Authority in 1997, and Tunisia in 1998), albeit some countries from other trade blocs have also signed one (such as Chile in 2003, Mexico in 2000, and South Africa in 2000).