Year	Percent
1990	64.09
1991	64.23
1992	64.31
1993	64.32
1994	64.29
1995	64.22
1996	64.26
1997	64.24
1998	64.2
1999	64.12
2000	64.01
2001	64.01
2002	63.92
2003	63.84
2004	63.71
2005	63.54
2006	63.5
2007	63.36
2008	63.24
2009	63.17
2010	63
2011	62.87
2012	62.73
2013	62.6
2014	62.46
2015	62.31
2016	62.01
2017	61.74
2018	61.55
2019	61.39
2020	59.58