Year	years
1960	66.1
1961	66.1
1962	66.1
1963	65.5
1964	65.2
1965	65
1966	65.5
1967	66
1968	65.6
1969	64.8
1970	65
1971	65.2
1972	65.4
1973	65.6
1974	66.6
1975	66.7
1976	66.6
1977	66.8
1978	66.8
1979	67
1980	67.3
1981	67.4
1982	67.2
1983	66.2
1984	67
1985	67.4
1986	67.9
1987	68.1
1988	68.3
1989	68.9
1990	69.4
1991	69.5
1992	69.5
1993	69.4
1994	69.6
1995	70.3
1996	70.8
1997	71
1998	71.1
1999	71.4
2000	71.9
2001	72.1
2002	72.3
2003	73.2
2004	73.5
2005	74.1
2006	74.55
2007	75
2008	75.4
2009	75.8
2010	76.3
2011	76.8
2012	77.1
2013	77.2
2014	78.2
2015	77.8
2016	78.2
2017	78.2
2018	78.5
2019	78.7
2020	77.8
2021	77.7
2022	78.6