Question: When did the UK vote to leave the organization which the Swiss have brought their economic practices into conformity with?

full_context: Document 1: Referendums in the United Kingdom: Until the latter half of the twentieth century the concept of a referendum was widely seen in British politics as ``unconstitutional ''and an`` alien device''. As of 2017, only three national referendums have ever been held across the whole of the United Kingdom: in 1975, 2011 and most recently in 2016.
Document 2: Brexit: In a referendum on 23 June 2016, 51.9% of the participating UK electorate voted to leave the EU, out of a turnout of 72.2%. On 29 March 2017, the UK government invoked Article 50 of the Treaty on the European Union. The UK is thus due to leave the EU at midnight on 30 March 2019 Central European Time (11 pm on 29 March 2019 GMT).
Document 3: Switzerland: In 2002 Switzerland became a full member of the United Nations, leaving the Vatican City as the last widely recognised state without full UN membership. Switzerland is a founding member of the EFTA, but is not a member of the European Economic Area. An application for membership in the European Union was sent in May 1992, but not advanced since the EEA was rejected in December 1992 when Switzerland was the only country to launch a referendum on the EEA. There have since been several referenda on the EU issue; due to a mixed reaction from the population the membership application has been frozen. Nonetheless, Swiss law is gradually being adjusted to conform with that of the EU, and the government has signed a number of bilateral agreements with the European Union. Switzerland, together with Liechtenstein, has been completely surrounded by the EU since Austria's entry in 1995. On 5 June 2005, Swiss voters agreed by a 55% majority to join the Schengen treaty, a result that was regarded by EU commentators as a sign of support by Switzerland, a country that is traditionally perceived as independent and reluctant to enter supranational bodies.
Document 4: Results of the 2016 United Kingdom European Union membership referendum: United Kingdom European Union membership referendum, 2016 Northern Ireland Choice Votes% Remain a member of the European Union 440,707 55.78% Leave the European Union 349,442 44.22% Valid votes 790,149 99.95% Invalid or blank votes 374 0.05% Total votes 790,523 100.00% Registered voters and turnout 1,260,955 62.69% Source: Electoral Commission
Document 5: Brexit: Brexit (/ ˈbrɛksɪt, ˈbrɛɡzɪt /) is the impending withdrawal of the United Kingdom (UK) from the European Union (EU). In a referendum on 23 June 2016, 51.9% of the participating UK electorate voted to leave the EU; the turnout was 72.2%. On 29 March 2017, the UK government invoked Article 50 of the Treaty on European Union. The European Union (Withdrawal) Act 2018 declares ``exit day ''to be 29 March 2019 at 11 pm UTC.
Document 6: 1975 United Kingdom European Communities membership referendum: The United Kingdom European Communities referendum of 1975, also known as the Common Market referendum and EEC membership referendum was non-binding referendum held on 5 June 1975 in the United Kingdom to gauge support for the country's continued membership of the European Communities (EC) -- often known at the time as the ``Common Market ''-- which it had entered on 1 January 1973 under the Conservative government of Edward Heath. Labour's manifesto for the October 1974 general election had promised that the people would decide`` through the ballot box'' whether to remain in the EC.
Document 7: 2016 United Kingdom European Union membership referendum: The planned referendum was included in the Queen's Speech on 27 May 2015. It was suggested at the time that Cameron was planning to hold the referendum in October 2016, but the European Union Referendum Act 2015, which authorised it, went before the House of Commons the following day, just three weeks after the election. On the bill's second reading on 9 June, members of the House of Commons voted by 544 to 53 in favour, endorsing the principle of holding a referendum, with only the Scottish National Party voting against. In contrast to the Labour Party's position prior to the 2015 general election under Miliband, acting Labour leader Harriet Harman committed her party to supporting plans for an EU referendum by 2017.To enable the referendum to take place, the European Union Referendum Act was passed by the Parliament of the United Kingdom. It extended to include and take legislative effect in Gibraltar, and received royal assent on 17 December 2015. The Act was, in turn, confirmed, enacted and implemented in Gibraltar by the European Union (Referendum) Act 2016 (Gibraltar), which was passed by the Gibraltar Parliament and entered into law upon receiving the assent of the Governor of Gibraltar on 28 January 2016.
Document 8: Switzerland: Switzerland joined the Council of Europe in 1963. In 1979 areas from the canton of Bern attained independence from the Bernese, forming the new canton of Jura. On 18 April 1999 the Swiss population and the cantons voted in favour of a completely revised federal constitution.In 2002 Switzerland became a full member of the United Nations, leaving the Vatican City as the last widely recognised state without full UN membership. Switzerland is a founding member of the EFTA, but is not a member of the European Economic Area. An application for membership in the European Union was sent in May 1992, but not advanced since the EEA was rejected in December 1992 when Switzerland was the only country to launch a referendum on the EEA. There have since been several referendums on the EU issue; due to opposition from the citizens, the membership application has been withdrawn. Nonetheless, Swiss law is gradually being adjusted to conform with that of the EU, and the government has signed a number of bilateral agreements with the European Union. Switzerland, together with Liechtenstein, has been completely surrounded by the EU since Austria's entry in 1995. On 5 June 2005, Swiss voters agreed by a 55% majority to join the Schengen treaty, a result that was regarded by EU commentators as a sign of support by Switzerland, a country that is traditionally perceived as independent and reluctant to enter supranational bodies.
Document 9: Switzerland: Switzerland has an overwhelmingly private sector economy and low tax rates by Western World standards; overall taxation is one of the smallest of developed countries. Switzerland is a relatively easy place to do business, currently ranking 20th of 189 countries in the Ease of Doing Business Index. The slow growth Switzerland experienced in the 1990s and the early 2000s has brought greater support for economic reforms and harmonization with the European Union. According to Credit Suisse, only about 37% of residents own their own homes, one of the lowest rates of home ownership in Europe. Housing and food price levels were 171% and 145% of the EU-25 index in 2007, compared to 113% and 104% in Germany.
Document 10: 2014 Scottish independence referendum: A referendum on Scottish independence from the United Kingdom took place on Thursday 18 September 2014. The referendum question, which voters answered with ``Yes ''or`` No'', was ``Should Scotland be an independent country? ''The`` No'' side won, with 2,001,926 (55.3%) voting against independence and 1,617,989 (44.7%) voting in favour. The turnout of 84.6% was the highest recorded for an election or referendum in the United Kingdom since the introduction of universal suffrage.
Document 11: Switzerland: Switzerland voted against membership in the European Economic Area in a referendum in December 1992 and has since maintained and developed its relationships with the European Union (EU) and European countries through bilateral agreements. In March 2001, the Swiss people refused in a popular vote to start accession negotiations with the EU. In recent years, the Swiss have brought their economic practices largely into conformity with those of the EU in many ways, in an effort to enhance their international competitiveness. The economy grew at 3% in 2010, 1.9% in 2011, and 1% in 2012. Full EU membership is a long-term objective of some in the Swiss government, but there is considerable popular sentiment against this supported by the conservative SVP party. The western French-speaking areas and the urban regions of the rest of the country tend to be more pro-EU, however with far from any significant share of the population.
Document 12: Brexit: In a referendum on 23 June 2016, 51.9% of the participating UK electorate voted to leave the EU, out of a turnout of 72.2%. On 29 March 2017, the UK government invoked Article 50 of the Treaty on the European Union. The UK is thus due to leave the EU on 29 March 2019.
Document 13: Switzerland: On 9 February 2014, Swiss voters narrowly approved by 50.3% a ballot initiative launched by the national conservative Swiss People's Party (SVP/UDC) to restrict immigration, and thus reintroducing a quota system on the influx of foreigners. This initiative was mostly backed by rural (57.6% approvals), suburban (51.2% approvals), and isolated cities (51.3% approvals) of Switzerland as well as by a strong majority (69.2% approval) in the canton of Ticino, while metropolitan centres (58.5% rejection) and the French-speaking part (58.5% rejection) of Switzerland rather rejected it. Some news commentators claim that this proposal de facto contradicts the bilateral agreements on the free movement of persons from these respective countries.
Document 14: Switzerland: Traditionally, Switzerland avoids alliances that might entail military, political, or direct economic action and has been neutral since the end of its expansion in 1515. Its policy of neutrality was internationally recognised at the Congress of Vienna in 1815. Only in 2002 did Switzerland become a full member of the United Nations and it was the first state to join it by referendum. Switzerland maintains diplomatic relations with almost all countries and historically has served as an intermediary between other states. Switzerland is not a member of the European Union; the Swiss people have consistently rejected membership since the early 1990s. However, Switzerland does participate in the Schengen Area.
Document 15: Switzerland: In 2006, Switzerland approved 1 billion francs of supportive investment in the poorer Southern and Central European countries in support of cooperation and positive ties to the EU as a whole. A further referendum will be needed to approve 300 million francs to support Romania and Bulgaria and their recent admission. The Swiss have also been under EU and sometimes international pressure to reduce banking secrecy and to raise tax rates to parity with the EU. Preparatory discussions are being opened in four new areas: opening up the electricity market, participation in the European GNSS project Galileo, cooperating with the European centre for disease prevention and recognising certificates of origin for food products.
ground_truth: 23 June 2016
sub_queries: In recent years, what have the Swiss brought their economic practices into conformity with? Answer: the EU
when did we decide to leave the the EU Answer: 23 June 2016