Year	years
1960	38.005
1961	38.515
1962	39.038
1963	39.594
1964	40.146
1965	40.736
1966	41.345
1967	41.964
1968	42.603
1969	43.234
1970	43.863
1971	44.469
1972	45.06
1973	45.597
1974	46.12
1975	46.609
1976	47.052
1977	47.456
1978	47.814
1979	48.107
1980	48.341
1981	48.59
1982	48.656
1983	48.749
1984	48.792
1985	48.816
1986	48.793
1987	48.715
1988	48.558
1989	48.305
1990	47.964
1991	47.57
1992	47.117
1993	46.682
1994	46.209
1995	45.731
1996	45.242
1997	44.786
1998	44.645
1999	44.509
2000	44.318
2001	44.424
2002	44.424
2003	44.963
2004	45.266
2005	45.625
2006	45.927
2007	46.483
2008	47.004
2009	47.545
2010	48.054
2011	48.801
2012	49.396
2013	49.205
2014	48.42
2015	51.167
2016	51.643
2017	51.552
2018	52.285
2019	53.048
2020	52.582
2021	51.645
2022	52.258