Year	Percent
1990	34.12257
1991	33.80659
1992	36.06286
1993	30.51712
1994	23.88345
1995	18.10952
1996	17.02829
1997	21.05926
1998	20.76129
1999	23.12501
2000	29.19952
2001	26.83256
2002	21.31374
2003	20.24322
2004	21.68936
2005	19.96745
2006	17.55447
2007	16.6823
2008	20.42891
2009	23.63573
2010	26.26527
2011	27.44909
2012	22.25713
2013	24.84359
2014	23.88823
2015	25.07806
2016	26.54642
2017	26.45803