Year	years
1960	50.364
1961	50.429
1962	50.409
1963	50.263
1964	50.189
1965	50.057
1966	50.148
1967	50.247
1968	50.431
1969	50.702
1970	51.012
1971	51.293
1972	51.722
1973	52.12
1974	52.372
1975	52.987
1976	53.487
1977	54.045
1978	54.669
1979	55.338
1980	56.058
1981	56.902
1982	57.565
1983	58.094
1984	58.635
1985	59.104
1986	59.455
1987	59.495
1988	59.62
1989	59.531
1990	59.398
1991	59.193
1992	58.555
1993	57.991
1994	58.018
1995	56.723
1996	55.232
1997	53.594
1998	51.783
1999	50.081
2000	48.427
2001	46.849
2002	45.595
2003	44.53
2004	43.711
2005	43.233
2006	42.914
2007	43.123
2008	43.566
2009	44.034
2010	45.596
2011	46.692
2012	47.835
2013	49.002
2014	50.033
2015	51.101
2016	52.264
2017	53.064
2018	53.733
2019	54.173
2020	54.693
2021	53.062
2022	53.036