Year	Percent
1990	51.09
1991	51.07
1992	51.02
1993	50.87
1994	50.86
1995	50.64
1996	50.52
1997	50.59
1998	50.53
1999	50.43
2000	50.46
2001	49.95
2002	49.45
2003	48.95
2004	48.47
2005	48.01
2006	47.55
2007	47.16
2008	46.78
2009	46.43
2010	46.08
2011	45.74
2012	45.42
2013	45.39
2014	45.36
2015	45.33
2016	45.3
2017	45.26
2018	45.36
2019	45.37
2020	44.56