Year	Percent
1992	36.22
1993	36.41
1994	36.59
1995	36.77
1996	36.95
1997	37.13
1998	37.31
1999	37.49
2000	37.67
2001	37.81
2002	37.94
2003	38.07
2004	38.21
2005	38.34
2006	38.52
2007	39.01
2008	39.19
2009	39.39
2010	39.57
2011	39.57
2012	39.57
2013	39.57
2014	39.57
2015	39.57