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	12
1983	12
1984	12
1985	12
1986	12
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