Year	Percent
1990	32.80663
1991	30.86438
1992	28.53084
1993	26.21654
1994	22.30162
1995	26.4145
1996	35.92072
1997	35.99749
1998	35.09649
1999	29.30404
2000	27.59632
2001	31.35666
2002	30.72373
2003	25.78402
2004	27.38086
2005	29.71257
2006	28.84372
2007	28.4831
2008	28.65847
2009	21.12363
2010	24.01346
2011	24.96627
2012	20.93538
2013	20.98284
2014	21.98608
2015	24.20443
2016	22.5704
2017	22.40174