Year	years
1960	71.23
1961	71.65
1962	71.37
1963	71.57
1964	71.66
1965	71.73
1966	71.82
1967	71.82
1968	71.69
1969	71.68
1970	72.22
1971	71.98
1972	72.04
1973	72.16
1974	72.2
1975	72.17
1976	72.14
1977	72.37
1978	72.43
1979	72.49
1980	72.78
1981	73.07
1982	73.42
1983	73.62
1984	73.85
1985	73.78
1986	73.98
1987	74.18
1988	74.15
1989	74.8
1990	74.81
1991	74.94
1992	75.35
1993	75.48
1994	76.06
1995	76.16
1996	76.52
1997	76.7
1998	76.9
1999	77.1
2000	77.4
2001	77.6
2002	77.7
2003	77.9
2004	78.4
2005	78.4
2006	78.7
2007	78.9
2008	79.1
2009	79.4
2010	79.5
2011	79.9
2012	79.9
2013	80.2
2014	80.4
2015	80.4
2016	80.6
2017	80.8
2018	80.9
2019	81.5
2020	80.6
2021	81.3
2022	81.5