Year	Percent
1990	14.84703
1991	13.46826
1992	7.05315
1993	9.6659
1994	11.07721
1995	11.85625
1996	11.86972
1997	15.10707
1998	18.53876
1999	19.12284
2000	17.74788
2001	15.31452
2002	17.05578
2003	17.90006
2004	18.85413
2005	18.54104
2006	21.12396
2007	19.6441
2008	19.0871
2009	17.12881
2010	16.03891
2011	16.97312
2012	15.88154
2013	16.68293
2014	16.6871
2015	17.33909
2016	17.11838
2017	17.80641