Year	years
1960	41.42254577644811
1961	41.73973935807562
1962	42.20072057552484
1963	42.440620261288736
1964	42.890837726942316
1965	43.02945129131192
1966	42.98409005214109
1967	43.23217833178633
1968	43.67073477598762
1969	43.91130716747807
1970	44.369830237344054
1971	44.87080396884152
1972	44.98734365716508
1973	45.708795356985526
1974	45.9204616638043
1975	46.30643270408786
1976	46.984952204866225
1977	47.447803211481514
1978	47.748586960162456
1979	48.210028914599825
1980	48.56903418099322
1981	48.93441927578173
1982	49.172894287908285
1983	48.328804574878326
1984	48.35866359939197
1985	48.60968158598791
1986	49.00427579865428
1987	49.33539730731276
1988	49.01742856729974
1989	49.882379792870196
1990	49.82184751909303
1991	49.69684178106943
1992	49.469336733924436
1993	49.69437855183005
1994	49.999480437919495
1995	50.111315440101414
1996	50.0458116077966
1997	50.21272239814784
1998	49.925086744592576
1999	50.638129068404666
2000	51.2619441016462
2001	51.533762631328365
2002	51.88907114846192
2003	52.367395929974094
2004	52.84661812154037
2005	53.46017793170976
2006	54.21136823960079
2007	54.847107811125895
2008	55.44886260821744
2009	56.21789288382959
2010	56.84569722907262
2011	57.557144064124756
2012	58.139480025035034
2013	58.66668186756227
2014	59.14134689295086
2015	59.56161718045812
2016	60.06772333147744
2017	60.475893074858405
2018	60.86196642952607
2019	61.24317607009691
2020	60.84749279160246
2021	60.24063783266549
2022	60.7631048177053