Year	Percent
1990	62.16
1991	61.95
1992	61.95
1993	62.27
1994	62.51
1995	62.22
1996	61.8
1997	61.32
1998	60.89
1999	61.11
2000	60.12
2001	58.73
2002	58.18
2003	60.15
2004	57.14
2005	56.18
2006	55.24
2007	55.58
2008	55.91
2009	56.66
2010	56.96
2011	57.85
2012	58.16
2013	58.28
2014	59.11
2015	59.26
2016	60.55
2017	60.91
2018	61.76
2019	61.99
2020	62.03