Year	Percent
1992	33.21
1993	33.28
1994	33.34
1995	33.4
1996	33.42
1997	33.49
1998	33.59
1999	33.65
2000	33.71
2001	33.78
2002	33.84
2003	33.91
2004	33.94
2005	34.01
2006	34.07
2007	34.13
2008	34.19
2009	34.25
2010	34.31
2011	34.32
2012	34.32
2013	34.33
2014	34.34
2015	34.35