Year	Percent
1998	13.387
1999	13.0685
2000	15.003
2001	13.7252
2002	13.9426
2003	11.8915
2004	10.9902
2005	9.5864
2006	6.4851
2007	6.0928
2008	7.7756
2009	19.1261
2010	21.2167
2011	17.3546
2012	14.8548
2013	11.827
2014	11.1983
2015	10.4415
2016	9.8365
2017	8.9997