Year	Percent
1976	27.22745
1977	27.28447
1978	28.11219
1996	41.18886
1999	45.93376
2000	50.73994
2001	53.40099
2002	57.37608
2004	63.16891
2005	67.07896
2006	70.77262
2007	72.16557
2008	75.27795
2009	79.38232
2010	81.79412
2011	84.73683
2012	84.25439
2013	84.48419
2014	83.84559
2015	82.08516