Year	Percent
1961	66.16345
1962	66.97198
1963	67.01844
1964	67.63826
1965	68.33793
1966	69.00421
1967	69.42372
1968	69.71839
1969	69.90855
1970	69.59355
1971	70.02468
1972	70.07403
1973	70.28596
1974	70.38467
1975	70.19161
1976	70.43112
1977	70.84918
1978	70.9145
1979	71.07272
1980	71.58514
1981	71.25998
1982	71.05821
1983	70.78676
1984	71.03208
1985	70.88982
1986	70.32806
1987	69.92307
1988	69.68355
1989	67.88649
1990	65.86442
1991	64.52025
1992	64.1051
1993	63.9759
1994	63.77704
1995	63.70591
1996	63.02511
1997	63.22601
1998	63.42691
1999	63.62781
2000	63.8142
2001	64.0151
2002	63.47801
2003	63.43446
2004	62.49093
2005	62.44738
2006	61.83771
2007	62.06997
2008	67.19408
2009	66.68486
2010	66.30861
2011	66.1199
2012	65.80055
2013	64.98766
2014	64.82799
2015	64.30541
2016	64.75541
2017	65.16185
2018	65.55378
2019	65.66991
2020	65.49572
2021	62.95544