The National Parliament of Papua New Guinea is the unicameral national legislature in Papua New Guinea. It was created in 1964 as the House of Assembly of Papua and New Guinea but gained its current name after the nation was granted independence in 1975. From 1964 until 1977 an Optional Preferential Voting System was used. The first past the post system was used from 1977 until 2002. Electoral reforms introduced by former Prime Minister Mekere Morauta introduced Limited Preferential Voting, in which voters numbered three preferred candidates. LPV was first used nationally in the 2007 election.