Year	Percent
1998	11.8595
1999	12.0616
2000	13.6053
2001	14.0999
2002	12.7842
2003	13.2003
2004	11.0656
2005	8.5348
2006	5.6114
2007	4.3288
2008	5.6281
2009	10.5213
2010	14.5189
2011	12.9104
2012	11.5732
2013	10.4784
2014	9.2213
2015	8.1612
2016	6.6531
2017	5.6759