Year	Percent
1991	25.84466
1992	22.83755
1993	23.95423
1994	22.08098
1995	30.25315
1996	34.74883
1997	31.78934
1998	34.63753
1999	32.93059
2000	31.80456
2001	30.26554
2002	30.75155
2003	35.94541
2004	27.39684
2005	34.81084
2006	33.84252
2007	36.96588
2008	49.59626
2009	50.05137
2010	43.5861
2011	50.71092
2012	55.19781
2013	55.29285
2014	55.93151
2015	56.99159
2016	56.66632
2017	56.76775