Year	Percent
1990	53.41
1991	53.13
1992	53.2
1993	52.78
1994	52.18
1995	51.46
1996	50.39
1997	49.54
1998	48.94
1999	48.69
2000	49.85
2001	49.44
2002	49.4
2003	49.73
2004	50.12
2005	50.5
2006	50.55
2007	50.54
2008	50.42
2009	50.29
2010	51.27
2011	52.42
2012	53.74
2013	54.67
2014	55.19
2015	56.05
2016	56.32
2017	55.94
2018	55.5
2019	55.88
2020	55.14