Year Percent 1974-01-01 98.39740000000000 1975-01-01 98.40340000000000 1976-01-01 98.15780000000000 1977-01-01 97.90350000000000 1978-01-01 91.87920000000000 1979-01-01 92.79320000000000 1980-01-01 98.07430000000000 1981-01-01 97.78860000000000 1982-01-01 97.38080000000000 1983-01-01 97.30190000000000 1984-01-01 97.45700000000001 1985-01-01 96.66799999999999 1986-01-01 93.40810000000000 1987-01-01 94.42060000000000 1988-01-01 98.14830000000000 1989-01-01 98.38330000000000 1990-01-01 98.48260000000000 1991-01-01 98.56750000000000 1992-01-01 98.59910000000000 1993-01-01 98.72590000000000 1994-01-01 96.76480000000000 1995-01-01 95.74680000000000 1996-01-01 97.67160000000000 1997-01-01 98.77090000000000 1998-01-01 98.93430000000000 1999-01-01 98.90680000000000 2000-01-01 98.81890000000000 2001-01-01 98.82160000000000 2002-01-01 97.43060000000000 2003-01-01 96.38020000000000 2004-01-01 96.46810000000000 2005-01-01 96.90630000000000 2006-01-01 97.85370000000000 2007-01-01 99.02240000000000 2008-01-01 99.71320000000000 2009-01-01 99.82580000000000 2010-01-01 99.75120000000000 2011-01-01 95.46720000000000 2012-01-01 95.46270000000000 2013-01-01 99.26960000000000 2014-01-01 99.58670000000000 2015-01-01 99.81500000000000 2016-01-01 95.96150000000000