Year	Percent
1998	35.99822
1999	20.86802
2000	17.49339
2001	18.02416
2002	21.06041
2003	19.66127
2004	21.2374
2005	21.27606
2006	16.93912
2007	16.4316
2008	18.22712
2009	18.61018
2010	20.43721
2011	20.12839
2012	21.31135
2013	24.11952
2014	25.5081