Year	Percent
1983	84.80041
1987	83.44559
1988	83.93276
1989	82.59732
1990	82.62965
1991	83.67246
1992	83.45158
1993	82.84784
1994	82.90177
1995	83.06718
1996	82.70367
1997	83.29724
1998	82.61448
1999	83.20836
2000	83.72083
2001	84.2041
2002	84.11005
2003	84.30827
2004	84.551
2005	83.90939
2006	83.80395
2007	83.81358
2008	84.11732
2009	83.30981
2010	83.74098
2011	83.49692
2012	83.3127
2013	82.35756
2014	83.09212
2015	82.22052
2016	82.53328
2017	83.44804