Year	Percent
1991	5.798
1992	8.925
1993	10.185
1994	12.95
1995	14.1334
1996	9.4963
1997	8.4485
1998	6.313
1999	3.472
2000	5.0161
2001	5.6887
2002	9.5243
2003	12.6801
2004	16.2466
2005	8.6312
2006	8.9015
2007	7.7301
2008	8.912
2009	19.744
2010	18.3708
2011	18.1515
2012	14.6948
2013	13.5541
2014	12.9314
2015	10.9328
2016	6.6612
2017	8.5871