Year	%
1997	19.71
2001	19.71
2002	19.71
2003	19.19
2004	19.19
2005	19.19
2006	19.19
2007	18.34
2008	18.34
2009	18.34
2010	18.34
2011	18.34
2013	17.85
2014	17.85
2015	17.85