Year	Percent
1990	87.06
1991	87.27
1992	87.52
1993	87.83
1994	87.95
1995	88.01
1996	88.04
1997	88.16
1998	88.23
1999	88.36
2000	88.53
2001	88.59
2002	88.57
2003	88.53
2004	88.46
2005	88.41
2006	87.62
2007	86.77
2008	85.87
2009	84.92
2010	83.9
2011	82.82
2012	81.68
2013	81.59
2014	81.5
2015	81.46
2016	81.47
2017	81.48
2018	81.47
2019	81.49