Year	Percent
1986	3.29
1987	3.09
1988	3.06
1989	2.73
1990	2.03
1991	2.16
1992	1.2
1993	1.27
1994	1.54
1995	1.47
1996	1.27
1997	1.11
1998	1.64
1999	1.38
2000	1.35
2001	1.13
2002	1
2003	1.04
2004	0.82
2005	0.93
2006	0.73
2007	0.71
2008	0.68
2009	0.63
2010	0.72
2011	0.45
2012	0.57
2013	0.59
2014	0.47
2015	0.44
2016	0.61
2017	0.44