Year	%
1996	19.1
1997	19.1
1998	19.1
1999	19.1
2000	19.1
2001	19.1
2002	19.1
2003	19.1
2004	19.1
2005	19.05
2006	19.05
2007	18.86
2008	18.86
2010	17.76
2011	17.76
2012	18.8
2013	18.8
2015	18.8
2019	18.94
2021	18.94