Year	Percent
1983	6.94
1985	6.17
1987	5.34
1988	4.86
1989	4.85
1990	5.08
1991	3.83
1992	2.62
1993	2.92
1994	2.52
1995	2.45
1996	2.1
1997	2.11
1998	1.8
1999	1.64
2000	1.59
2001	1.36
2002	1.09
2003	0.94
2004	0.86
2005	0.96
2006	0.97
2007	0.92
2008	0.77
2009	0.74
2010	1.07
2011	1.01
2012	0.85
2013	0.79
2014	0.81
2015	0.86
2016	0.71
2017	0.53