Year	Percent
1990	79.82
1991	82.17
1992	82.6
1993	81.76
1994	81
1995	79.91
1996	79.36
1997	80.4
1998	79.94
1999	79.22
2000	78.87
2001	78.28
2002	77.94
2003	78.06
2004	78.18
2005	78.28
2006	78.33
2007	78.38
2008	78.44
2009	77.49
2010	78.35
2011	81.32
2012	78.32
2013	75.87
2014	76.69
2015	79.86
2016	80.65
2017	81.08
2018	83.12
2019	84.09