Year	%
1997	18.18
1998	18.11
2000	18.11
2001	18.11
2003	18.05
2004	18
2005	18
2006	18
2007	17.96
2008	17.96
2009	17.96
2010	17.96
2011	17.92
2012	17.96
2014	17.96
2015	17.77
2017	17.77
2018	17.71
2019	17.71
2020	17.71
2021	17.71