Year	Percent
1980	0.4
1986	0
1987	0
1991	1.1
1992	2.1
1993	2.4
1994	2.3
1995	4.1
1996	4.6
1997	4.1
1998	4.6
1999	4.8
2000	5.7
2001	9.4
2002	14
2003	7
2004	5.4
2005	3.9
2006	3.3
2007	2.9
2008	2.6
2009	2.6
2010	1.1
2011	0.9
2012	0.8
2013	0.8
2014	0.7
2016	0.6