Year	Percent
1990	46.92
1991	46.78
1992	46.64
1993	46.5
1994	46.37
1995	46.23
1996	46.09
1997	45.95
1998	45.81
1999	45.67
2000	45.54
2001	45.4
2002	45.26
2003	45.12
2004	44.97
2005	44.83
2006	44.69
2007	44.55
2008	44.41
2009	44.27
2010	44.13
2011	44.45
2012	44.76
2013	45.08
2014	45.39
2015	45.71