Year	Percent
1990	85.04
1991	84.63
1992	84.38
1993	84.16
1994	84.03
1995	83.94
1996	83.95
1997	83.91
1998	84.54
1999	84.99
2000	85.31
2001	85.5
2002	85.61
2003	85.65
2004	85.3
2005	84.92
2006	84.5
2007	84.04
2008	83.55
2009	83.01
2010	82.42
2011	81.79
2012	81.12
2013	80.39
2014	79.62
2015	78.79
2016	78.64
2017	78.46
2018	78.26
2019	78.07
2020	76.13