Year	years
1960	39.345
1961	39.74
1962	40.225
1963	40.513
1964	40.917
1965	41.428
1966	41.733
1967	42.104
1968	42.519
1969	42.935
1970	43.394
1971	43.915
1972	44.48
1973	45.05
1974	45.683
1975	44.909
1976	46.762
1977	47.343
1978	47.953
1979	48.623
1980	49.248
1981	49.807
1982	50.479
1983	50.942
1984	51.612
1985	52.219
1986	52.803
1987	53.28
1988	53.947
1989	54.124
1990	54.962
1991	55.362
1992	55.807
1993	56.205
1994	56.639
1995	56.819
1996	57.123
1997	56.76
1998	56.898
1999	57.267
2000	57.309
2001	57.69
2002	57.579
2003	57.758
2004	57.804
2005	57.895
2006	58.217
2007	58.333
2008	58.799
2009	58.943
2010	59.324
2011	59.56
2012	60.011
2013	60.227
2014	60.633
2015	60.811
2016	61.288
2017	61.455
2018	61.808
2019	62.009
2020	61.975
2021	61.245
2022	61.522