Year	Percent
1990	50.78
1991	50.66
1992	50.66
1993	50.64
1994	50.73
1995	50.63
1996	50.42
1997	50.24
1998	50.03
1999	49.82
2000	49.64
2001	49.38
2002	49.18
2003	49.02
2004	48.88
2005	48.75
2006	48.51
2007	48.26
2008	48.03
2009	47.84
2010	47.7
2011	47.52
2012	47.42
2013	47.36
2014	47.33
2015	47.34
2016	47.41
2017	47.5
2018	47.61
2019	47.74
2020	47.5