Year	Percent
1991	33.05
1992	33.05
1993	32.96
1994	32.88
1995	32.74
1996	32.67
1997	32.67
1998	32.67
1999	32.69
2000	32.81
2001	33.01
2002	33.13
2003	33.26
2004	33.43
2005	33.54
2006	33.37
2007	33.21
2008	33.02
2009	32.61
2010	32.44
2011	32.52
2012	32.59
2013	32.59
2014	32.68
2015	32.77
2016	32.87
2017	33.02
2018	33.17
2019	33.29