This "does not" mean that there are no checks and balances. With the introduction of a parliamentary system, political parties started to form quickly, which led to a call for electoral reform that saw the introduction of Party-list proportional representation in 1918. The peculiarities of the Norwegian election system generate 6–8 parties and make it extremely difficult for a single party to gain an absolute majority. It has only occurred for a brief period in the aftermath of World War II where the Labour Party had an absolute majority.