Year	Percent
1990	0.584
1991	1.415
1992	3.875
1993	6.458
1994	7.227
1995	10.385
1996	10.553
1997	11.15
1998	10.4427
1999	12.9246
2000	15.0229
2001	13.0373
2002	11.3143
2003	12.1416
2004	11.6271
2005	9.153
2006	6.2343
2007	5.3831
2008	5.7582
2009	16.6768
2010	19.2737
2011	13.0586
2012	10.9111
2013	9.0888
2014	7.8585
2015	6.2364
2016	7.4159
2017	6.1933