Year	Percent
1991	52.34
1992	52.45
1993	52.52
1994	52.54
1995	53.39
1996	53.16
1997	50.58
1998	49.91
1999	52.19
2000	53.28
2001	52.23
2002	51.45
2003	50.83
2004	52.17
2005	54.23
2006	56.6
2007	58.43
2008	59.64
2009	58.06
2010	57.02
2011	56.16
2012	56.41
2013	54.62
2014	55.58
2015	56.51
2016	57.42
2017	58.38
2018	59.1
2019	61.16
2020	57.51