Year	Percent
1987	10.37
1988	10.28
1989	10.94
1990	9.03
1991	12.84
1992	13.04
1993	11.15
1994	8.62
1995	8.72
1996	14.07
1997	12.64
1998	15.92
1999	19.25
2000	6.436
2001	5.205
2003	6.1567
2004	5.7046
2005	4.7028
2006	4.3629
2007	3.9042
2008	4.9843
2009	5.8571
2010	4.9497
2011	4.2701
2012	3.8135
2013	3.6533
2014	4.1286
2015	4.497
2016	5.8124
2017	4.8972