Year	Percent
1991	50.86
1992	50.81
1993	50.64
1994	50.43
1995	50.18
1996	50.23
1997	50.2
1998	50.1
1999	49.91
2000	49.74
2001	50.02
2002	50.13
2003	50.22
2004	50.3
2005	50.36
2006	50.83
2007	51.25
2008	51.53
2009	51.45
2010	51.36
2011	51.95
2012	52.39
2013	52.72
2014	52.98
2015	53.11
2016	52.72
2017	52.27
2018	51.76
2019	51.18