Year	Percent
1998	13.4781
1999	15.46987
2000	12.10712
2001	13.20403
2004	16.01496
2005	15.48265
2007	12.46448
2008	12.38985
2009	15.6267
2010	15.65498
2011	14.95252
2012	15.15711
2013	16.96951
2014	17.47282
2015	17.79541
2016	17.64241