Year	Percent
1976	73.16604
1977	82.71225
1978	75.86978
1979	79.92079
1981	81.9393
1982	89.07589
1983	94.78001
1984	93.05525
1985	89.69026
1987	85.90212
1988	83.75519
1989	90.05977
2005	72.90558
2006	80.60256
2007	70.09181
2008	82.05779
2009	84.48091
2010	87.38862
2011	87.20472
2012	88.28481
2013	88.14032
2014	92.0955
2015	93.2176
2016	91.94039