Year	Percent
1997	11.93273
1998	12.63323
1999	13.37269
2000	11.90123
2001	11.87808
2002	14.43059
2003	15.37671
2004	16.66983
2005	15.31758
2006	15.16415
2007	15.09628
2008	16.35748
2009	16.81947
2010	16.85512
2011	16.31663
2012	15.24938
2013	14.3308
2014	14.18679
2015	13.59302
2016	13.94762