Year Percent 1979-01-01 94.56490000000000 1980-01-01 95.30320000000000 1981-01-01 96.49260000000000 1982-01-01 96.19100000000000 1983-01-01 95.74350000000000 1984-01-01 93.69290000000000 1985-01-01 91.81870000000000 1986-01-01 92.35200000000000 1987-01-01 92.03590000000000 1988-01-01 92.83010000000000 1989-01-01 95.41280000000000 1990-01-01 96.16530000000000 1991-01-01 96.04210000000000 1992-01-01 97.35880000000000 1993-01-01 98.25750000000000 1994-01-01 98.67840000000000 1995-01-01 99.18010000000000 1996-01-01 99.35440000000000 1997-01-01 99.48760000000000 1998-01-01 99.62920000000000 1999-01-01 99.69660000000000 2000-01-01 99.61260000000000 2001-01-01 99.50690000000000 2002-01-01 99.43850000000000 2003-01-01 99.51799999999999 2004-01-01 99.56310000000000 2005-01-01 99.52860000000000 2006-01-01 99.56880000000000 2007-01-01 99.56920000000000 2008-01-01 99.58080000000000 2009-01-01 99.25040000000000 2010-01-01 98.98040000000000 2011-01-01 99.00060000000000 2012-01-01 99.39190000000000 2013-01-01 99.82320000000000 2014-01-01 99.82460000000000 2015-01-01 99.84890000000000 2016-01-01 99.92550000000000