Year	years
1960	29.754
1961	29.83
1962	29.939
1963	30.154
1964	30.418
1965	30.623
1966	30.871
1967	31.212
1968	31.631
1969	32.045
1970	32.532
1971	32.937
1972	33.86
1973	34.565
1974	35.426
1975	36.225
1976	37.195
1977	38.106
1978	39.062
1979	39.953
1980	40.751
1981	41.215
1982	41.824
1983	42.142
1984	42.699
1985	43.207
1986	43.977
1987	44.693
1988	45.393
1989	45.877
1990	46.62
1991	47.216
1992	47.496
1993	47.733
1994	47.742
1995	47.816
1996	47.792
1997	48.531
1998	49.164
1999	49.797
2000	50.539
2001	51.284
2002	52.222
2003	52.893
2004	53.538
2005	54.003
2006	54.615
2007	54.941
2008	55.291
2009	55.874
2010	56.382
2011	56.755
2012	57.079
2013	57.357
2014	57.9
2015	58.363
2016	58.731
2017	59.132
2018	59.393
2019	59.664
2020	58.633
2021	58.941
2022	59.417