Year	years
1960	45.73248728023604
1961	46.049930223643415
1962	46.4417351119141
1963	46.75528222988432
1964	47.130907671869565
1965	46.16301520062406
1966	46.706996974675626
1967	47.0858496269617
1968	48.63141063387873
1969	49.02446102151955
1970	48.91463832165454
1971	46.72015500146668
1972	50.212543433768275
1973	50.66877727605774
1974	51.155454666733924
1975	51.69501736555071
1976	52.14539447541576
1977	52.495119570943125
1978	52.88947378225075
1979	53.25051276359521
1980	53.66848493961172
1981	54.122058767452494
1982	54.536881102508204
1983	54.99945113755345
1984	55.38710424480926
1985	55.81726350991519
1986	56.34649135708144
1987	56.696330439333785
1988	57.06168720408899
1989	57.4248305454691
1990	57.8899662403253
1991	58.0493377100052
1992	58.68476291618827
1993	59.07711417153992
1994	59.4575650755285
1995	59.82475712258755
1996	60.21375961183133
1997	60.62682568776879
1998	61.14430021669782
1999	61.72096420551729
2000	61.975819911748275
2001	62.30969894674026
2002	62.70203507909003
2003	63.04012037163557
2004	63.29916583471778
2005	63.58406850071081
2006	63.92689744859014
2007	64.10843936222992
2008	64.34508176155184
2009	64.620714239661
2010	65.07808307062317
2011	65.46214949155677
2012	65.93393540871469
2013	66.42039876459846
2014	67.02769331672762
2015	67.5944489238994
2016	68.09001549083699
2017	68.43589058113062
2018	68.70592846494523
2019	68.87221023585398
2020	68.0443600410197
2021	65.89397632884685
2022	66.42971881283724