Year	Percent
1990	79.86
1991	80.15
1992	80.39
1993	80.75
1994	81.16
1995	81.25
1996	81.4
1997	81.6
1998	81.75
1999	82.01
2000	82.07
2001	82.3
2002	82.49
2003	82.34
2004	82.33
2005	82.25
2006	82.18
2007	82.12
2008	82.15
2009	82.53
2010	82.81
2011	82.74
2012	82.83
2013	83.12
2014	83.44
2015	83.77
2016	83.96
2017	84.38
2018	84.64
2019	84.89