Year	years
1960	42.676
1961	43.367
1962	43.76
1963	44.309
1964	44.708
1965	44.77
1966	42.323
1967	44.99
1968	45.144
1969	45.127
1970	45.01
1971	45.153
1972	43.717
1973	43.853
1974	41.546
1975	41.604
1976	44.523
1977	44.507
1978	44.561
1979	45.224
1980	45.549
1981	45.937
1982	46.175
1983	37.944
1984	38.351
1985	39.111
1986	39.491
1987	47.304
1988	47.045
1989	47.101
1990	46.758
1991	47.866
1992	48.276
1993	48.711
1994	49.1
1995	49.422
1996	49.872
1997	50.508
1998	50.934
1999	50.777
2000	51.198
2001	51.644
2002	52.317
2003	53.436
2004	54.249
2005	55.338
2006	56.528
2007	58.062
2008	59.416
2009	60.962
2010	61.849
2011	62.874
2012	63.804
2013	64.895
2014	65.361
2015	66.326
2016	67.341
2017	67.533
2018	68.397
2019	68.795
2020	68.426
2021	68.285
2022	68.903