However, as was the case with the proportional representation system voted by the previous parliament in 2016, the two thirds supermajority required by the constitution for a new electoral system to be immediately applied in the next election was not met, and, therefore, the new system will be applied to the election after next. Greek citizens aged 17 and over on the year of the election are eligible to vote, and at the age of 25 and over are also eligible to be elected to Parliament. Women's suffrage was adopted in 1952. Constituencies Constituencies in Greece have traditionally been multi-seat, and they mostly coincide with prefectures. The number of seats is adjusted once every ten years, following the decennial population census. Prefecture constituencies may not be deprived of representation, nor may they be merged with another prefecture; they may however be split into smaller constituencies if their population increases disproportionately: this was the case with the Athens B constituency which was split into three smaller constituencies in 2019. Population changes have left nine (Kefalonia, Lefkas, Eurytania, Grevena, Samos, Thesprotia, Kastoria, Phocis and Zakynthos) prefectures with a single parliamentary seat each, whereas some urban or suburban constituencies have seen large increases in their seat allotment over the years. Following the census of 2021, the largest constituencies can be found in the metropolitan areas of Athens and Thessaloniki. These are Athens B3 (19 seats), Thessaloniki A (17 seats), Athens B1 (16 seats), Athens A (13 seats), Athens B2 (12 seats) and East Attica (12 seats). The remaining constituencies elect single-digit numbers of MPs. The largest constituency outside Athens and Thessaloniki is Achaea which has 9 seats. Voting Polling takes place in school buildings on a Sunday, a festive occasion for students who are then given a four-day weekend off. The procedure is run by a presiding judge or attorney-at-law appointed by the local Bar association, and secretarially assisted by local citizens selected by lot in a process resembling jury duty. Local party representatives are allowed to monitor tallying; their theoretical role is to ensure transparency. Police presence varies as police officers might be allocated to stand guard at an individual polling centre or supervise-that is, to patrol the general vicinity of-more than one polling centre (especially in the countryside). Up until 1998, the responsibility of guarding polling stations was shared between the Hellenic Armed Forces and the Hellenic Police, while there was