Year	Percent
1990	49.07
1991	49.19
1992	49.31
1993	49.39
1994	49.41
1995	49.38
1996	49.31
1997	49.22
1998	49.13
1999	49.07
2000	49.05
2001	49.17
2002	49.33
2003	49.51
2004	49.67
2005	49.8
2006	49.66
2007	49.49
2008	49.32
2009	49.16
2010	49.03
2011	49.13
2012	49.27
2013	49.46
2014	49.65
2015	49.86
2016	50.03
2017	50.21
2018	50.35
2019	50.49