Year	Percent
1990	80.28
1991	80.53
1992	80.77
1993	81
1994	81.21
1995	81.41
1996	81.65
1997	81.89
1998	82.11
1999	82.3
2000	82.47
2001	82.6
2002	82.73
2003	82.84
2004	82.94
2005	83.03
2006	83.14
2007	83.25
2008	83.31
2009	83.44
2010	83.46
2011	83.69
2012	83.88
2013	84.12
2014	84.33
2015	84.52
2016	84.7
2017	84.87
2018	85.06
2019	85.2