Year	%
1997	31.79
1999	31.79
2000	31.62
2001	31.62
2002	31.62
2003	31.62
2004	31.62
2005	31.62
2006	31.62
2007	32.57
2008	32.92
2009	32.91
2010	33.14
2012	33.72
2013	33.82
2018	32.46
2019	32.46
2020	32.46
2021	32.46