Year	Percent
1991	54.16
1992	54.95
1993	55.42
1994	55.67
1995	55.74
1996	55.93
1997	56.06
1998	56.2
1999	56.31
2000	56.5
2001	56.47
2002	56.28
2003	55.65
2004	55.2
2005	55.01
2006	54.86
2007	54.74
2008	55.74
2009	55.66
2010	55.15
2011	57.18
2012	57.08
2013	57.31
2014	57.37
2015	57.41
2016	55
2017	56.1
2018	57.26
2019	59.62
2020	60.24