Year	Percent
1990	50.16
1991	50.09
1992	49.87
1993	49.9
1994	50.22
1995	50
1996	50.34
1997	50.83
1998	51.19
1999	51.73
2000	52.84
2001	52.15
2002	53.73
2003	54.87
2004	55.74
2005	56.86
2006	57.63
2007	58.11
2008	58.84
2009	59.05
2010	59.3
2011	59.29
2012	59.3
2013	58.97
2014	58.61
2015	58.49
2016	58.31
2017	57.99
2018	57.76
2019	57.69
2020	56.25