Year Percent 1960-01-01 84.96770000000000 1961-01-01 85.60100000000000 1962-01-01 87.78600000000000 1963-01-01 89.52860000000000 1964-01-01 90.39970000000000 1965-01-01 90.94920000000000 1966-01-01 90.43350000000000 1967-01-01 90.30700000000000 1968-01-01 90.39110000000000 1969-01-01 89.88230000000000 1970-01-01 89.06380000000000 1971-01-01 88.46320000000000 1972-01-01 89.26370000000000 1973-01-01 91.42970000000000 1974-01-01 90.31180000000000 1975-01-01 88.79820000000000 1976-01-01 89.52940000000000 1977-01-01 90.57090000000000 1978-01-01 91.20600000000000 1979-01-01 88.86330000000000 1980-01-01 88.13370000000000 1981-01-01 88.63450000000000 1982-01-01 87.78390000000000 1983-01-01 89.39470000000000 1984-01-01 88.90890000000000 1985-01-01 86.55580000000000 1986-01-01 85.59899999999999 1987-01-01 85.20030000000000 1988-01-01 87.01930000000000 1989-01-01 89.46250000000000 1990-01-01 92.37140000000000 1991-01-01 90.77900000000000 1992-01-01 86.40299999999999 1993-01-01 87.13970000000000 1994-01-01 89.43840000000000 1995-01-01 90.71330000000000 1996-01-01 92.21910000000000 1997-01-01 93.57070000000000 1998-01-01 95.53270000000000 1999-01-01 96.99560000000000 2000-01-01 97.75850000000000 2001-01-01 99.42550000000000 2002-01-01 99.98800000000000 2003-01-01 99.99390000000000 2004-01-01 99.99900000000000 2005-01-01 99.99890000000000 2006-01-01 99.99799999999999 2007-01-01 99.99910000000000 2008-01-01 99.99910000000000 2009-01-01 99.99910000000000 2010-01-01 99.99910000000000 2011-01-01 99.99910000000000 2012-01-01 99.96820000000000 2013-01-01 99.87310000000000 2014-01-01 99.80000000000000 2015-01-01 98.43810000000000 2016-01-01 96.15200000000000