upon a request of 427,939 Dutch citizens, based on the Advisory Referendum Act 2015. United Kingdom's European Union membership, 2016 — 2016 United Kingdom European Union membership referendum, 23 June 2016, 51.9% to leave, turnout 72.2% In February 2016, the Conservative government of David Cameron negotiated "a new settlement for Britain in the EU" which was then followed by a referendum on the UK's membership of the European Union in the United Kingdom and Gibraltar. The result was for the UK to leave the EU and the deal was discarded. The United Kingdom formally withdrew from the EU on 31 January 2020. Hungarian migrant quota referendum, 2016 — 2016 Hungarian migrant quota referendum, 2 October 2016, 98.4% against, turnout 44.0% A referendum was held to decide whether Hungary should accept migrant quotas imposed by the EU without the National Assembly's approval or not. The turnout was too low to make the poll valid. Danish EU opt-out referendum, 2022 – 2022 Danish European Union opt-out referendum, 1 June 2022, 66.8% in favour, turnout 65.7% A referendum on the abolition of Denmark's opt-out from the European Union's defense cooperation. Future EU enlargements Countries which seek to join the European Union in the future may hold a referendum as part of the accession process. In addition, Article 88-5 of the Constitution of France requires a referendum there to ratify any future accession treaty. Politicians in other existing members have proposed referendums in their states, particularly with reference to the accession of Turkey. There is discussion amongst eurosceptic parties and movements across the EU to hold their own referendums on EU membership since the referendum in the UK. Agreements between Switzerland and the EU — 1972: Free trade agreement with the EC, 72.5% in favour — 1992: EEA Agreement with all EU member states and all EFTA member states as well as the European Communities, 50.3% against — 1997: Requiring the approval of a referendum and the Cantons to launch accession negotiations with the EU, 74.1% against — 2000: Bilateral I agreements with the EU, 67.2% in favour — 2001: Opening negotiations for EU membership, 76.8% against — 2005: Schengen Agreement and the Dublin Regulation, 54.6% in favour — 2005: Freedom of movement for workers, to include 10 new EU members, 56.0% in favour — 2006: Cohesion contribution of one billion for the ten new member states of the EU, 53.4% in favour —