Year	years
1960	36.2
1961	36.487
1962	36.679
1963	37.069
1964	37.22
1965	37.582
1966	37.784
1967	35.94
1968	36.911
1969	37.244
1970	38.78
1971	39.68
1972	40.488
1973	41.331
1974	42.106
1975	42.922
1976	43.887
1977	44.597
1978	44.957
1979	45.187
1980	45.23
1981	45.504
1982	45.434
1983	45.571
1984	45.473
1985	45.126
1986	44.841
1987	44.745
1988	44.729
1989	44.788
1990	44.597
1991	44.197
1992	44.145
1993	44.232
1994	44.079
1995	44.004
1996	44.052
1997	44.385
1998	44.89
1999	45.446
2000	46.095
2001	46.58
2002	46.867
2003	47.377
2004	47.785
2005	48.362
2006	48.901
2007	49.258
2008	49.678
2009	50.182
2010	50.483
2011	50.92
2012	51.094
2013	51.295
2014	51.383
2015	51.477
2016	51.848
2017	52.017
2018	52.331
2019	52.651
2020	52.456
2021	52.285
2022	53.295