Year	Percent
1990	83.06
1991	82.91
1992	82.79
1993	82.69
1994	82.6
1995	82.52
1996	82.46
1997	82.48
1998	82.59
1999	83.29
2000	83.23
2001	83.17
2002	83.47
2003	83.72
2004	83.91
2005	84
2006	84.12
2007	84.01
2008	83.82
2009	83.61
2010	83.39
2011	83.18
2012	82.98
2013	82.83
2014	82.66
2015	82.51
2016	82.35
2017	82.31
2018	82.25
2019	82.16