Year	years
1960	30.493
1961	30.563
1962	30.693
1963	30.869
1964	31.114
1965	31.417
1966	31.597
1967	31.964
1968	32.379
1969	32.82
1970	33.302
1971	33.731
1972	34.771
1973	35.574
1974	36.556
1975	37.384
1976	38.325
1977	39.206
1978	40.152
1979	40.98
1980	41.637
1981	41.954
1982	42.525
1983	42.611
1984	43.214
1985	43.645
1986	44.419
1987	45.221
1988	45.987
1989	46.24
1990	47.098
1991	47.58
1992	47.895
1993	48.327
1994	48.318
1995	48.169
1996	47.906
1997	48.74
1998	49.348
1999	49.905
2000	50.689
2001	51.602
2002	52.776
2003	53.579
2004	54.346
2005	54.851
2006	55.487
2007	55.74
2008	56.097
2009	56.753
2010	57.328
2011	57.723
2012	58.08
2013	58.463
2014	58.969
2015	59.468
2016	59.704
2017	60.235
2018	60.694
2019	60.841
2020	59.94
2021	60.331
2022	60.832