Year	Percent
1990	35.89
1991	35.79
1992	35.69
1993	35.59
1994	35.49
1995	35.4
1996	35.3
1997	35.2
1998	35.1
1999	35
2000	34.91
2001	34.83
2002	34.75
2003	34.67
2004	34.59
2005	34.51
2006	34.45
2007	34.39
2008	34.33
2009	34.27
2010	34.21
2011	34.16
2012	34.11
2013	34.07
2014	34.02
2015	33.97