Year	Percent
1990	76.08
1991	76.53
1992	77.11
1993	77.82
1994	78.39
1995	79.06
1996	79.65
1997	80.11
1998	79.89
1999	80.59
2000	81.05
2001	81.47
2002	81.27
2003	81.72
2004	81.96
2005	82.4
2006	82.95
2007	83.54
2008	85.15
2009	85.5
2010	85.84
2011	86.39
2012	86.73
2013	86.88
2014	87.57
2015	88.24
2016	88.42
2017	88.73
2018	88.46
2019	88.57