Year	Percent
1990	76.09
1991	76.99
1992	77.47
1993	78
1994	79.12
1995	79.42
1996	80.3
1997	81.75
1998	82.31
1999	83.02
2000	83.59
2001	84.26
2002	84.79
2003	85.18
2004	85.93
2005	85.41
2006	85.98
2007	86.6
2008	87.72
2009	87.9
2010	87.8
2011	87.45
2012	87.68
2013	87.46
2014	87.11
2015	87.14
2016	86.98
2017	86.72
2018	87.06
2019	87.45