Year	Percent
1986	2.4636
1987	2.9592
1988	2.8472
1989	1.9326
1990	1.9316
1991	2.0027
1992	2.7586
1993	4.2117
1994	4.6491
1995	4.8796
1996	5.893
1997	6.4335
1998	3.7725
1999	4.5279
2000	3.7615
2001	2.4297
2002	3.2527
2003	4.9235
2004	6.2995
2005	6.8547
2006	7.2475
2007	7.1138
2008	7.2805
2009	8.2273
2010	9.9239
2011	11.9209
2012	14.5098
2013	14.6622
2014	15.1793
2015	13.9475
2016	12.6225
2017	8.9776