Year	Percent
1970	81.1072
1971	88.40559
1972	92.69809
1973	93.13005
1974	91.1258
1975	90.82839
1976	91.8324
1977	89.01821
1983	96.56574
2011	94.13282
2012	96.31496
2013	95.86981
2014	95.25498
2015	93.79384
2016	93.18898