Year	Percent
1983	8.5555
1984	8.9637
1985	8.9224
1986	7.6293
1987	6.5423
1988	6.9599
1989	8.0004
1990	8.4355
1991	9.5057
1992	9.2398
1993	10.4586
1994	9.0068
1995	7.5553
1996	7.6196
1997	5.7323
1998	6.0956
1999	4.9366
2000	4.6708
2001	4.098
2002	4.2157
2003	5.5592
2004	5.0955
2005	4.5397
2006	3.9969
2007	3.582
2008	2.8092
2009	4.6061
2010	5.8544
2011	6.9353
2012	6.8019
2013	6.8729
2014	6.4253
2015	6.1069
2016	6.3592
2017	5.5227