Year	Percent
1990	80.23
1991	80.66
1992	82.37
1993	81.55
1994	82.1
1995	83.03
1996	83.13
1997	83.2
1998	83.23
1999	83.39
2000	83.95
2001	85.51
2002	85.01
2003	85.25
2004	84.57
2005	85.01
2006	85.08
2007	85.76
2008	86.55
2009	87.11
2010	87.05
2011	87.82
2012	87.82
2013	87.32
2014	87.72
2015	87.93
2016	87.93
2017	88.21
2018	87.87
2019	87.98