National elections are universal for all citizens 18 years and older. National elections for the executive and legislative branches take place every five years. Members of the judicial branch (justices) are appointed by the head of state. Panama's National Assembly is elected by proportional representation in fixed electoral districts, so many smaller parties are represented. Presidential elections requires a simple majority; out of the five last presidents only ex-president Ricardo Martinelli has managed to be elected with over 50 percent of the popular vote.