Year	Percent
1991	5.789
1992	6.086
1993	6.395
1994	8.347
1995	15.339
1996	12.327
1997	10.473
1998	8.737
1999	6.132
2000	6.224
2001	6.702
2002	8.2624
2003	9.8803
2004	11.5095
2005	8.1961
2006	8.0945
2007	8.1979
2008	8.7162
2009	11.2292
2010	10.504
2011	10.7519
2012	10.3168
2013	10.7458
2014	10.7554
2015	10.0074
2016	8.7108
2017	7.9812