Year	Percent
1988	13.45061
1989	14.61325
1990	15.53673
1991	15.04018
1992	14.83451
1993	15.15306
1994	16.7832
1995	15.99297
1996	16.8885
1997	18.42619
1998	18.22871
1999	19.98533
2000	21.43657
2001	20.82228
2002	22.45632
2003	20.19696
2004	20.31241
2005	19.60682
2006	18.44725
2007	16.97935
2008	15.57597
2009	17.50202
2010	13.93702
2011	13.74682
2012	14.21611
2013	14.32994
2014	14.42057
2015	15.9629
2016	15.6724