Year	Percent
1990	77.38
1991	77.35
1992	77.34
1993	77.2
1994	77.21
1995	77.14
1996	77.15
1997	77.2
1998	77.25
1999	77.35
2000	77.41
2001	77.42
2002	77.4
2003	77.37
2004	77.37
2005	77.42
2006	77.55
2007	77.7
2008	77.87
2009	78.03
2010	78.19
2011	78.37
2012	78.54
2013	78.69
2014	78.48
2015	78.29
2016	78.05
2017	77.82
2018	77.59
2019	77.31