Year	Percent
1990	83.03
1991	82.83
1992	82.63
1993	82.43
1994	82.23
1995	82.03
1996	81.83
1997	81.63
1998	81.43
1999	81.23
2000	81.03
2001	80.84
2002	80.64
2003	80.45
2004	80.26
2005	80.06
2006	79.86
2007	79.66
2008	79.46
2009	79.26
2010	79.06
2011	78.86
2012	78.66
2013	78.46
2014	78.26
2015	78.06