Year	years
1960	36.585
1961	34.704
1962	34.95
1963	35.247
1964	35.539
1965	35.884
1966	36.144
1967	36.466
1968	36.837
1969	37.192
1970	37.543
1971	37.933
1972	38.313
1973	38.642
1974	39.026
1975	38.397
1976	38.303
1977	38.575
1978	38.99
1979	39.344
1980	39.63
1981	39.997
1982	40.274
1983	39.118
1984	39.367
1985	39.712
1986	39.948
1987	37.575
1988	38.322
1989	38.557
1990	38.674
1991	41.009
1992	39.189
1993	38.161
1994	39.733
1995	43.885
1996	44.118
1997	44.35
1998	42.582
1999	42.455
2000	43.562
2001	43.714
2002	44.94
2003	47.568
2004	48.532
2005	49.508
2006	50.227
2007	51.473
2008	52.527
2009	53.537
2010	54.415
2011	55.314
2012	56.22
2013	56.925
2014	57.606
2015	58.213
2016	58.741
2017	59.331
2018	59.582
2019	59.977
2020	59.584
2021	59.029
2022	59.351