Year	Percent
1990	0.13
1991	0.4
1992	0.99
1993	2.87
1994	4.33
1996	7.17
1997	8.13
1998	9.94
1999	9.07
2001	10.28
2002	9.72
2003	8.7
2004	9.25
2005	8.41
2006	9.36
2007	7.47
2008	9.01
2009	8.09
2010	7.59
2011	7.65
2012	6.34
2013	7.11
2014	5.56
2015	11.46
2016	9.8
2017	10.78