Year	Percent
1991	28.7385
1992	27.58635
1993	23.16796
1994	25.37467
1995	39.14828
1996	41.8458
1997	47.87357
1998	52.84823
1999	55.51831
2000	66.67746
2001	64.73485
2002	57.97194
2003	56.25067
2004	59.53509
2005	62.54943
2006	73.98228
2007	77.94397
2008	79.28947
2009	74.4104
2010	81.82944
2011	86.74504
2012	86.40542
2013	85.6593
2014	87.65438
2015	90.21258
2016	89.53683
2017	90.09005