Year	Percent
1990	62.14
1991	62.31
1992	62.43
1993	62.48
1994	61.99
1995	61.47
1996	61.11
1997	60.8
1998	60.55
1999	60.34
2000	60.14
2001	59.79
2002	59.4
2003	59.56
2004	59.59
2005	59.47
2006	59.36
2007	59.15
2008	58.88
2009	58.66
2010	58.52
2011	58.4
2012	58.37
2013	58.39
2014	58.41
2015	58.42
2016	58.47
2017	58.52
2018	58.56
2019	58.64