Year	Percent
1971	36.3393
1999	76.35451
2000	81.71895
2002	94.50691
2004	88.57807
2006	87.21432
2007	93.38497
2009	92.44317
2010	90.81339
2011	92.16612
2012	91.81596
2013	91.29311
2014	90.44835
2015	92.61459
2016	90.92557