Year	Percent
1999	14.10189
2000	10.50399
2001	12.79616
2002	11.76528
2003	11.62248
2004	17.95759
2005	65.43131
2006	39.37517
2007	31.84478
2008	27.28044
2009	32.68154
2010	27.48651
2011	26.58733
2012	25.34833
2013	26.02982
2014	25.06575
2015	26.34893
2016	25.25097
2017	26.84138