Year	Percent
1990	77.98
1991	78.54
1992	79.11
1993	79.71
1994	80.19
1995	80.28
1996	80.67
1997	81.09
1998	81.32
1999	81.25
2000	81.25
2001	81.14
2002	80.69
2003	80.99
2004	81.31
2005	80.92
2006	80.9
2007	80.6
2008	80.27
2009	80.84
2010	80.6
2011	80.87
2012	80.95
2013	80.76
2014	80.12
2015	80.52
2016	80.91
2017	81.27
2018	82.37
2019	82.58