Year	Percent
1991	52.81
1992	52.85
1993	52.85
1994	52.37
1995	51.92
1996	51.55
1997	51.24
1998	50.97
1999	50.7
2000	50.49
2001	50.1
2002	49.61
2003	49.77
2004	49.89
2005	49.93
2006	50.08
2007	49.9
2008	49.63
2009	49.13
2010	48.84
2011	48.52
2012	48.25
2013	48
2014	47.81
2015	47.6
2016	47.43
2017	47.3
2018	47.15
2019	47.17
2020	43.22