Year	Percent
1991	2.49
1992	2.1
1993	2.2
1994	2.4
1995	4.1
1996	4.7
1997	3.7
1998	5.6
1999	8
2000	8.6
2001	8.1
2002	7.9
2003	7.1
2004	5.6
2005	4.4
2006	3.8
2007	3.5
2008	3.2
2009	4.2
2010	3.52
2011	2.98
2012	2.27
2013	2.23
2014	1.9
2015	1.97
2016	2.3
2017	2.4