Year	Percent
1961	83.53461
1962	82.5454
1963	81.60565
1964	80.57935
1965	79.6396
1966	79.48627
1967	79.25875
1968	79.07657
1969	78.88615
1970	78.69573
1971	78.5053
1972	78.319
1973	78.12446
1974	77.9464
1975	77.73949
1976	77.54495
1977	77.53588
1978	77.5433
1979	77.53423
1980	77.53341
1981	77.52434
1982	77.51527
1983	77.51527
1984	77.51527
1985	77.51527
1986	77.8178
1987	78.02389
1988	78.22997
1989	78.55971
1990	78.80701
1991	79.14087
1992	79.52666
1993	79.90833
1994	80.17954
1995	80.38975
1996	80.69475
1997	80.74009
1998	80.77554
1999	80.83324
2000	80.88847
2001	80.79615
2002	80.80851
2003	80.72608
2004	80.46229
2005	80.35925
2006	79.86876
2007	79.87041
2008	80.05012
2009	79.9512
2010	79.87124
2011	79.44505
2012	79.41785
2013	79.41785
2014	79.41785
2015	79.41785
2016	79.41785
2017	79.41785
2018	79.41785
2019	79.41785
2020	79.41785
2021	79.41785