Year	Percent
1990	51.81
1991	51.65
1992	51.46
1993	51.37
1994	51.43
1995	51.21
1996	51.02
1997	50.99
1998	50.85
1999	50.9
2000	50.65
2001	50.59
2002	50.49
2003	50.5
2004	50.45
2005	50.31
2006	50.19
2007	50.32
2008	50.25
2009	50.11
2010	49.91
2011	50.03
2012	50.09
2013	50.13
2014	50.03
2015	50.04
2016	50.16
2017	50.22
2018	50.14
2019	50.1