Year	Percent
1990	50.26
1991	50.06
1992	49.99
1993	49.87
1994	49.68
1995	49.53
1996	49.71
1997	49.73
1998	49.79
1999	49.9
2000	49.9
2001	50.32
2002	49.96
2003	49.63
2004	48.14
2005	48.25
2006	48.46
2007	49.18
2008	49.26
2009	49.37
2010	49.99
2011	50.84
2012	52.05
2013	53.48
2014	54.38
2015	54.55
2016	55.17
2017	55.69
2018	56.98
2019	57.86
2020	58.25