Year	Percent
1990	51.05
1991	51.1
1992	51.01
1993	51.09
1994	51.13
1995	51.15
1996	51.23
1997	51.32
1998	51.01
1999	50.7
2000	50.38
2001	50.06
2002	49.73
2003	49.4
2004	49.09
2005	48.79
2006	49.18
2007	49.46
2008	49.87
2009	50.36
2010	50.61
2011	51.08
2012	51.94
2013	51.6
2014	51.57
2015	51.59
2016	51.57
2017	51.56
2018	51.53
2019	51.53