Year	Percent
1983	18.0752
1984	12.4173
1985	10.0469
1986	7.0118
1987	7.953
1988	8.1408
1989	10.6931
1990	11.4337
1991	10.735
1992	12.1337
1993	14.4852
1994	10.1606
1995	7.7878
1996	8.9692
1997	6.6084
1998	6.701
1999	9.4667
2000	6.5066
2001	7.3232
2002	8.8286
2003	10.623
2004	8.4691
2005	8.6457
2006	7.8875
2007	7.6366
2008	7.4048
2009	13.27
2010	16.0901
2011	15.6893
2012	14.7591
2013	14.2743
2014	13.7412
2015	11.6095
2016	13.088
2017	11.4091