Year	Percent
1991	45.69
1992	46.08
1993	45.5
1994	45.29
1995	45.69
1996	45.55
1997	45.9
1998	45.96
1999	47.36
2000	48.76
2001	47.59
2002	47.42
2003	47.13
2004	47.95
2005	48.68
2006	48.63
2007	49.58
2008	49.86
2009	49.16
2010	49.49
2011	49.28
2012	49.13
2013	48.99
2014	48.99
2015	48.91
2016	49.06
2017	49.6
2018	50.51
2019	51.02
2020	50.13