Year	Percent
1990	53.65
1991	53.5
1992	53.38
1993	53.24
1994	53.08
1995	52.77
1996	52.61
1997	52.38
1998	52.05
1999	51.72
2000	51.46
2001	51.3
2002	51.22
2003	51.05
2004	50.91
2005	50.79
2006	50.8
2007	50.24
2008	49.67
2009	49.1
2010	48.51
2011	47.96
2012	47.39
2013	46.83
2014	46.25
2015	45.66
2016	45.68
2017	45.66
2018	45.66
2019	45.65
2020	44.27