Year	years
1970	6
1971	6
1972	6
1973	6
1974	6
1975	6
1976	6
1977	7
1978	8
1979	8
1980	8
1981	8
1982	8
1983	8
1984	8
1985	8
1986	8
1987	8
1988	8
1989	8
1990	8
1991	7
1992	7
1993	7
1994	7
1995	7
1996	7
1997	7
1998	7
1999	7
2000	7
2001	7
2002	7
2003	7
2004	7
2005	7
2006	7
2007	7
2008	7
2009	7
2010	7
2011	7
2012	7
2013	7
2014	7
2015	7
2016	7
2017	7
2018	7
2019	7
2020	7
2021	7
2022	7
2023	7