Year	Percent
1999	20.54
2000	20.0955
2001	21.2099
2002	24.2563
2003	23.734
2004	27.4418
2005	29.823
2006	27.3249
2007	25.2873
2008	21.3605
2009	20.6074
2010	18.8157
2011	19.3469
2012	15.9708
2013	16.06
2014	16.0852
2015	17.0415
2016	15.8249
2017	15.6251