This interactive diagram shows the number of seats held in Parliament by each political party after elections since the introduction of the mixed-member proportional (MMP) voting system in 1996. One effect of MMP is to lessen the dominance of the major parties. In none of these elections did one party gain a majority of the parliamentary seats. A government was subsequently formed either as a formal coalition between parties or as a result of two-tier agreements in which smaller parties were given ministerial posts outside Cabinet in return for signing confidence and supply agreements with the dominant party. After each of the first seven MMP elections, the largest party in Parliament led the government and the largest party’s leader became prime minister. The 2017 election had a different sequel, with National remaining the largest party in Parliament but consigned to opposition by a coalition between Labour and New Zealand First that was supported by the Green Party.