Year	Percent
1961	78.66504
1962	77.8938
1963	77.57414
1964	77.5186
1965	77.23839
1966	76.95812
1967	76.82222
1968	76.70852
1969	76.54184
1970	76.40587
1971	76.19206
1972	76.09203
1973	75.96977
1974	75.38068
1975	75.2473
1976	75.11951
1977	74.79991
1978	74.44704
1979	73.96575
1980	73.70704
1981	73.42603
1982	73.22283
1983	73.10859
1984	72.91945
1985	72.75256
1986	72.57454
1987	72.44103
1988	72.29331
1989	72.14866
1990	72.03739
1991	71.88161
1992	68.2764
1993	68.21723
1994	68.1282
1995	68.76252
1996	68.81816
1997	68.98664
1998	68.96437
1999	68.88641
2000	65.32024
2001	65.44298
2002	65.26445
2003	65.44298
2004	65.43182
2005	65.42797
2006	64.82535
2007	64.80304
2008	64.61332
2009	63.87938
2010	59.01911
2011	58.95283
2012	58.96388
2013	58.06915
2014	57.68135
2015	57.68135
2016	57.87859
2017	58.1087
2018	58.032
2019	57.83476
2020	53.87544
2021	55.26724