Year	years
1960	37.5
1961	37.974
1962	38.393
1963	38.774
1964	39.24
1965	39.554
1966	39.882
1967	40.09
1968	40.38
1969	40.722
1970	41.09
1971	41.483
1972	41.848
1973	42.252
1974	42.243
1975	42.24
1976	42.656
1977	43.175
1978	43.561
1979	43.972
1980	44.585
1981	44.905
1982	44.86
1983	45.323
1984	45.777
1985	46.145
1986	47.075
1987	47.333
1988	48.015
1989	47.828
1990	49.769
1991	50.607
1992	52.465
1993	53.234
1994	54.1
1995	54.914
1996	55.756
1997	56.312
1998	49.158
1999	43.397
2000	56.111
2001	58.298
2002	58.811
2003	59.409
2004	59.899
2005	60.597
2006	61.611
2007	62.116
2008	62.573
2009	63.328
2010	63.787
2011	64.402
2012	64.838
2013	65.067
2014	65.6
2015	66.033
2016	66.289
2017	66.577
2018	67.067
2019	67.3
2020	67.133
2021	66.536
2022	66.604