Year	Percent
1990	85.48
1991	85.5
1992	85.61
1993	85.67
1994	85.7
1995	85.72
1996	85.78
1997	85.75
1998	85.74
1999	85.77
2000	85.87
2001	85.81
2002	85.78
2003	85.87
2004	85.84
2005	85.87
2006	85.77
2007	85.67
2008	85.62
2009	85.53
2010	85.5
2011	85.32
2012	85.14
2013	85.55
2014	85.49
2015	85.41
2016	85.47
2017	85.57
2018	85.68
2019	85.82