Year	Percent
1990	62.43
1991	62.3
1992	62.19
1993	62.06
1994	61.93
1995	61.78
1996	61.64
1997	61.56
1998	61.88
1999	61.83
2000	61.71
2001	61.63
2002	61.46
2003	61.32
2004	61.19
2005	61.14
2006	60.95
2007	60.79
2008	60.22
2009	60.46
2010	60.37
2011	61.58
2012	62.6
2013	64.06
2014	64.29
2015	64.46
2016	64.32
2017	64.4
2018	64.78
2019	64.73
2020	64.19