Year	Percent
1990	78.86
1991	78.97
1992	79.43
1993	79.83
1994	80.16
1995	80.45
1996	80.64
1997	80.83
1998	81.02
1999	81.24
2000	81.5
2001	81.74
2002	81.83
2003	81.99
2004	82.18
2005	82.4
2006	82.53
2007	82.67
2008	82.82
2009	82.99
2010	83.18
2011	83.33
2012	83.48
2013	83.63
2014	83.77
2015	83.89
2016	84.01
2017	84.11
2018	85.04
2019	83.34