Year	years
1960	51.4
1961	53.059
1962	54.584
1963	56.191
1964	57.835
1965	59.251
1966	60.733
1967	62.101
1968	63.471
1969	64.454
1970	65.616
1971	66.851
1972	67.645
1973	68.461
1974	69.109
1975	69.799
1976	70.457
1977	70.777
1978	71.339
1979	71.637
1980	72.173
1981	72.362
1982	72.808
1983	72.976
1984	73.115
1985	73.178
1986	73.283
1987	73.333
1988	73.34
1989	73.671
1990	73.701
1991	73.599
1992	73.995
1993	74.352
1994	74.702
1995	75.111
1996	75.963
1997	76.367
1998	76.636
1999	76.716
2000	77.48
2001	77.669
2002	77.908
2003	77.97
2004	78.253
2005	78.723
2006	78.941
2007	79.469
2008	79.719
2009	79.901
2010	79.966
2011	80.109
2012	80.369
2013	80.646
2014	80.813
2015	80.84
2016	81.033
2017	81.116
2018	81.195
2019	81.319
2020	80.433
2021	80.018
2022	80.497