Year	Percent
1990	24.73
1991	24.73
1992	24.67
1993	24.67
1994	24.6
1995	24.6
1996	24.6
1997	24.53
1998	24.53
1999	24.47
2000	24.47
2001	24.47
2002	24.47
2003	24.4
2004	24.4
2005	24.4
2006	24.4
2007	24.33
2008	24.33
2009	24.27
2010	24.27
2011	24.27
2012	24.2
2013	24.2
2014	24.13
2015	24.13