Year	Percent
1990	76.2
1991	76.47
1992	76.69
1993	76.79
1994	76.82
1995	77.02
1996	77.15
1997	77.44
1998	77.57
1999	77.52
2000	77.77
2001	78.02
2002	77.88
2003	77.77
2004	78.46
2005	78.91
2006	80.33
2007	80.2
2008	80.25
2009	80.18
2010	80.65
2011	80.74
2012	80.42
2013	80.58
2014	80.64
2015	80.72
2016	80.37
2017	80.12
2018	79.74
2019	78.47