Year	Percent
1990	48.55
1991	48.32
1992	48.09
1993	47.85
1994	47.62
1995	47.38
1996	47.15
1997	46.92
1998	46.68
1999	46.45
2000	46.22
2001	45.98
2002	45.75
2003	45.51
2004	45.28
2005	45.05
2006	44.84
2007	44.63
2008	44.42
2009	44.22
2010	44.01
2011	43.8
2012	43.59
2013	43.39
2014	43.18
2015	42.97