Year	years
1970	11
1971	11
1972	11
1973	11
1974	11
1975	10
1976	10
1977	10
1978	10
1979	10
1980	10
1981	10
1982	10
1983	11
1984	11
1985	11
1986	11
1987	12
1988	12
1989	12
1990	12
1991	12
1992	12
1993	12
1994	12
1995	12
1996	12
1997	12
1998	13
1999	13
2000	13
2001	13
2002	13
2003	13
2004	13
2005	13
2006	13
2007	13
2008	13
2009	13
2010	13
2011	13
2012	13
2013	13
2014	13
2015	13
2016	13
2017	13
2018	13
2019	13
2020	13
2021	13
2022	13
2023	13