Year	Percent
1970	82.76118
1971	90.73258
1972	95.20838
1973	96.84013
1974	94.55132
1975	94.10133
1976	95.03838
1977	90.63753
1983	97.69396
2011	94.39723
2012	96.62311
2013	95.22198
2014	95.40864
2015	93.66435
2016	92.35038