Year	Percent
1990	64.95
1991	64.74
1992	64.65
1993	64.5
1994	64.47
1995	64.21
1996	63.86
1997	63.56
1998	63.23
1999	62.93
2000	62.71
2001	62.43
2002	62.25
2003	62.14
2004	62.07
2005	62.01
2006	61.84
2007	61.69
2008	61.56
2009	61.49
2010	61.5
2011	61.45
2012	61.5
2013	61.6
2014	61.71
2015	61.81
2016	61.92
2017	62.02
2018	62.12
2019	62.24