Year	Percent
1990	84.24
1991	84.18
1992	84.14
1993	84.11
1994	84.06
1995	83.96
1996	83.82
1997	83.62
1998	83.36
1999	83.01
2000	82.58
2001	81.9
2002	81.1
2003	80.25
2004	79.45
2005	78.78
2006	78.24
2007	77.84
2008	77.52
2009	77.19
2010	76.79
2011	76.69
2012	76.58
2013	76.46
2014	76.35
2015	76.26
2016	76.19
2017	76.12
2018	76.02
2019	75.88