Year	years
1960	68.7
1961	68.4
1962	68.5
1963	68.5
1964	68.5
1965	68.3
1966	68.1
1967	68.4
1968	68.1
1969	68.4
1970	68.2
1971	68.7
1972	69
1973	68.4
1974	68.9
1975	69
1976	69.3
1977	68.9
1978	69.8
1979	69.8
1980	70
1981	70.5
1982	70.7
1983	70.8
1984	71.2
1985	71
1986	71
1987	71.3
1988	71.4
1989	71.8
1990	72.5
1991	73.3
1992	73.1
1993	73.8
1994	74.2
1995	74.1
1996	74.3
1997	74.7
1998	75.5
1999	75.5
2000	76.1
2001	76.4
2002	76.7
2003	77
2004	77.5
2005	77.9
2006	78
2007	78.2
2008	78.4
2009	78.8
2010	79.1
2011	79.4
2012	79.7
2013	79.6
2014	79.73
2015	79.91
2016	80
2017	80.2
2018	80
2019	80.3
2020	80.5
2021	80.5
2022	81.2