Year	Percent
1961	85.01318
1962	84.84848
1963	84.84848
1964	84.91436
1965	84.91436
1966	85.07905
1967	85.07905
1968	83.43215
1969	81.62055
1970	79.94071
1971	77.86561
1972	77.70092
1973	77.70092
1974	77.70092
1975	78.26087
1976	77.70092
1977	75.49407
1978	75.52701
1979	76.05402
1980	75.62582
1981	75.82345
1982	75.49407
1983	75.32938
1984	75.79051
1985	76.02108
1986	75.46113
1987	76.74572
1988	77.17391
1989	75.92227
1990	76.44928
1991	76.51515
1992	76.94335
1993	76.87747
1994	76.71278
1995	76.54809
1996	76.61397
1997	76.71278
1998	76.71278
1999	76.71278
2000	76.87747
2001	76.87747
2002	75.88933
2003	75.88933
2004	76.21871
2005	76.6469
2006	75.98814
2007	76.71278
2008	77.79974
2009	77.04216
2010	76.61397
2011	76.15283
2012	75.27339
2013	74.17984
2014	74.97694
2015	73.22134
2016	77.60211
2017	79.64427
2018	80.14822
2019	80.13834
2020	80.13834
2021	80.13834