Year	Percent
1990	76.5
1991	76.34
1992	76.56
1993	76.77
1994	76.95
1995	77.12
1996	77.12
1997	77.15
1998	77.27
1999	77.5
2000	77.83
2001	78.15
2002	78.58
2003	79.11
2004	79.7
2005	80.32
2006	80.83
2007	81.36
2008	81.84
2009	82.22
2010	82.47
2011	81.96
2012	82.08
2013	82.01
2014	81.86
2015	81.68
2016	82.14
2017	82.73
2018	83.36
2019	83.86