Year	years
1960	67.7857142857143
1961	67.9
1962	67.84
1963	67.78
1964	67.72
1965	67.66
1966	67.6
1967	67.64
1968	67.68
1969	67.72
1970	67.76
1971	67.8
1972	68.16
1973	68.52
1974	68.88
1975	69.24
1976	69.6
1977	69.92
1978	70.24
1979	70.56
1980	70.88
1981	71.2
1982	71.5
1983	71.8
1984	72.1
1985	72.4
1986	72.7
1987	73.02
1988	73.34
1989	73.66
1990	73.98
1991	74.3
1992	74.5
1993	75
1994	75
1995	75
1996	75.2
1997	75.7
1998	75.9
1999	76.2
2000	76.6
2001	77
2002	77.4
2003	77.8
2004	78.1
2005	78.5
2006	78.7
2007	79
2008	79.2
2009	79.3
2010	79.5
2011	79.7
2012	79.9
2013	80.1
2014	80.3
2015	80.4
2016	80.4
2017	80.5
2018	80.7
2019	80.9
2020	81.2
2021	81.3
2022	81.2