Year	Percent
1990	80.86
1991	81.31
1992	81.72
1993	81.65
1994	81.58
1995	81.57
1996	81.9
1997	82.33
1998	82.18
1999	82.02
2000	82.03
2001	82.3
2002	82.19
2003	82.33
2004	82.34
2005	82.63
2006	82.94
2007	83.36
2008	83.5
2009	83.85
2010	84.08
2011	83.93
2012	84.13
2013	84.84
2014	85.21
2015	85.51
2016	86.07
2017	86.62
2018	87.43
2019	87.93