Year	Percent
1961	57.87836
1962	57.95502
1963	58.03168
1964	58.116
1965	58.12367
1966	58.19266
1967	58.22946
1968	58.23099
1969	58.25552
1970	58.27086
1971	58.31685
1972	58.33525
1973	58.33709
1974	58.33878
1975	58.33878
1976	58.33832
1977	58.33832
1978	58.33832
1979	58.33678
1980	58.33678
1981	58.34292
1982	58.34445
1983	58.34445
1984	58.34445
1985	58.34445
1986	58.34445
1987	58.33065
1988	58.32298
1989	58.32298
1990	58.32298
1991	58.30765
1992	58.30765
1993	58.16046
1994	57.97495
1995	57.89829
1996	57.88909
1997	57.94735
1998	58.05927
1999	57.89982
2000	57.94582
2001	57.94735
2002	57.93968
2003	58.0838
2004	58.15127
2005	58.1344
2006	58.12367
2007	58.1298
2008	58.13287
2009	58.13287
2010	58.1344
2011	58.13133
2012	58.1298
2013	58.12367
2014	58.12367
2015	58.12367
2016	58.12367
2017	58.12367
2018	58.27699
2019	58.27699
2020	58.74155
2021	58.74155