Year	Percent
1991	49.3
1992	49.56
1993	49.85
1994	50.15
1995	50.43
1996	50.97
1997	51.48
1998	51.99
1999	52.55
2000	53.19
2001	52.64
2002	52.18
2003	51.82
2004	51.52
2005	51.26
2006	50.83
2007	50.5
2008	50.22
2009	49.66
2010	52.44
2011	55.46
2012	58.52
2013	61.59
2014	64.65
2015	64.3
2016	63.49
2017	64.41
2018	65.27
2019	65.95
2020	62.87