Year	Percent
1990	76.13
1991	76.22
1992	76.31
1993	76.39
1994	76.45
1995	76.49
1996	76.55
1997	76.56
1998	76.39
1999	76.39
2000	76.43
2001	76.41
2002	76.47
2003	76.56
2004	76.68
2005	76.8
2006	76.85
2007	76.92
2008	76.46
2009	77.38
2010	77.58
2011	78.7
2012	79.67
2013	81.42
2014	81.97
2015	82.44
2016	82.34
2017	82.51
2018	82.72
2019	82.72