The lower house of the Oireachtas (Irish parliament), Dáil Éireann, contains 166 Teachtaí Dála (TDs), representing 43 parliamentary constituencies throughout the Republic of Ireland. Depending on its size, each constituency must have at least 3 members. The most recent (Census 2011) ratio indicates that there is one TD for every 27,640 people. Elections are held using the single transferable vote form of proportional representation.