Year	Percent
1990	77.45
1991	77.45
1992	77.38
1993	77.32
1994	77.22
1995	77.08
1996	76.94
1997	76.83
1998	76.77
1999	76.75
2000	76.66
2001	76.6
2002	76.55
2003	76.47
2004	76.36
2005	76.25
2006	76.16
2007	76.05
2008	76
2009	75.98
2010	76.29
2011	76.52
2012	76.75
2013	77.74
2014	77.9
2015	77.95
2016	77.51
2017	77.62
2018	77.69
2019	77.37
2020	75.63