Year	Percent
1990	77.68
1991	77.92
1992	78.2
1993	78.38
1994	78.47
1995	78.5
1996	78.57
1997	78.63
1998	78.68
1999	78.72
2000	78.77
2001	78.75
2002	78.69
2003	78.58
2004	78.4
2005	78.27
2006	78.09
2007	77.89
2008	77.7
2009	78.78
2010	78.15
2011	78.66
2012	77.55
2013	78.14
2014	78.91
2015	78.75
2016	77.09
2017	77.91
2018	78.25
2019	80.43