Year	Percent
1990	78.2
1991	78.24
1992	78.32
1993	78.86
1994	79.37
1995	79.86
1996	80.32
1997	80.74
1998	81.13
1999	81.49
2000	81.82
2001	82.1
2002	82.35
2003	83.61
2004	84.78
2005	85.86
2006	86.86
2007	87.78
2008	88.63
2009	89.42
2010	90.14
2011	89.13
2012	89.18
2013	89.21
2014	89.26
2015	89.37
2016	89.44
2017	89.49
2018	89.54
2019	89.59