Year	years
1970	12
1971	12
1972	12
1973	12
1974	12
1975	12
1976	12
1977	13
1978	14
1979	14
1980	14
1981	14
1982	14
1983	14
1984	14
1985	14
1986	14
1987	14
1988	14
1989	14
1990	14
1991	13
1992	13
1993	13
1994	13
1995	13
1996	13
1997	13
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