Year	Percent
1990	48.79
1991	48.78
1992	48.58
1993	48.63
1994	48.62
1995	48.58
1996	48.49
1997	48.43
1998	47.99
1999	47.54
2000	47.1
2001	46.68
2002	46.26
2003	45.85
2004	45.47
2005	45.12
2006	45.58
2007	45.71
2008	45.93
2009	46.35
2010	46.7
2011	46.98
2012	47.65
2013	47.19
2014	47.13
2015	47.09
2016	46.96
2017	46.8
2018	46.6
2019	46.44
2020	45.91