Year	years
1970	12
1971	12
1972	12
1973	12
1974	12
1975	12
1976	12
1977	12
1978	12
1979	12
1980	12
1981	12
1982	13
1983	13
1984	13
1985	13
1986	13
1987	13
1988	13
1989	13
1990	13
1991	13
1992	13
1993	13
1994	13
1995	13
1996	13
1997	13
1998	12
1999	12
2000	12
2001	12
2002	12
2003	12
2004	12
2005	12
2006	12
2007	12
2008	12
2009	12
2010	12
2011	12
2012	12
2013	12
2014	12
2015	12
2016	12
2017	12
2018	12
2019	12
2020	12
2021	12
2022	12
2023	12