Year	Percent
1990	50.47
1991	50.58
1992	48.77
1993	48.3
1994	47.74
1995	47.34
1996	47.41
1997	47.35
1998	47.54
1999	47.74
2000	47.72
2001	47.9
2002	48.34
2003	48.75
2004	49.52
2005	48.95
2006	48.89
2007	48.61
2008	48.93
2009	48.29
2010	48.03
2011	47.97
2012	48.9
2013	48.56
2014	48.82
2015	48.74
2016	49.28
2017	49.61
2018	49.71
2019	49.72
2020	48.4