Year	Percent
1986	1.87
1987	2.22
1988	1.75
1989	1.38
1991	1.08
1992	0.95
1993	0.9
1994	1.09
1995	1.17
1996	1.2
1997	1.06
1998	1.11
1999	1.15
2000	0.36
2001	1.02
2002	0.86
2003	0.82
2004	0.78
2006	0.67
2007	0.79
2008	0.65
2009	0.62
2010	0.55
2011	0.74
2012	0.63
2013	0.53
2014	0.54
2015	0.38
2016	0.51
2017	0.47