Year	Percent
1983	92.72116
1984	92.26332
1985	93.21651
1986	93.31159
1987	93.25508
1988	93.11932
1989	93.16193
1990	93.21557
1991	94.04243
1992	93.83892
1993	93.54495
1994	93.25954
1995	92.97413
1996	93.04166
1997	92.84919
1998	92.77253
1999	93.10209
2000	92.97563
2001	92.44798
2002	92.58521
2003	92.55031
2004	91.91437
2005	91.32381
2006	91.40614
2007	91.43681
2008	91.78992
2009	92.15183
2010	92.13359
2011	92.04831
2012	92.14697
2013	92.32681
2014	92.44498
2015	92.61985
2016	92.67743
2017	92.76897