Year	Percent
1986	7.06
1987	6.48
1988	5.46
1989	4.72
1990	4.01
1991	5.87
1992	2.36
1993	2.45
1994	2.74
1995	2.59
1996	2.01
1997	1.93
1998	3.02
1999	2.75
2000	3.36
2001	3.66
2002	2.82
2003	2.16
2004	2.16
2005	2.05
2006	1.77
2007	1.46
2008	1.16
2009	1.11
2010	1.19
2011	0.79
2012	0.76
2013	0.75
2014	0.6
2015	0.58
2016	0.65
2017	0.49