Year	years
1970	5
1971	6.5
1972	6.5
1973	6.5
1974	6.5
1975	6.5
1976	6.5
1977	6.5
1978	6.5
1979	6.5
1980	6.5
1981	6.5
1982	6.5
1983	6.5
1984	6.5
1985	6.5
1986	6.5
1987	6.5
1988	6.5
1989	6.5
1990	6.5
1991	6.5
1992	6.5
1993	6.5
1994	6.5
1995	6.5
1996	6.5
1997	6.5
1998	6.5
1999	6.5
2000	6.5
2001	6.5
2002	6.5
2003	6.5
2004	6.5
2005	6.5
2006	6.5
2007	6.5
2008	6.5
2009	6.5
2010	6.5
2011	6.5
2012	6.5
2013	6.5
2014	6.5
2015	6.5
2016	6.5
2017	6.5
2018	6.5
2019	6.5
2020	6.5
2021	6.5
2022	6.5
2023	6.5