Year Percent 1960-01-01 78.92710000000000 1961-01-01 79.77910000000000 1962-01-01 80.81260000000000 1963-01-01 82.37040000000000 1964-01-01 84.21640000000000 1965-01-01 83.40740000000000 1966-01-01 82.19130000000000 1967-01-01 82.59200000000001 1968-01-01 80.89520000000000 1969-01-01 78.91640000000000 1970-01-01 78.99120000000000 1971-01-01 80.76680000000000 1972-01-01 82.74490000000000 1973-01-01 83.76240000000000 1974-01-01 83.68020000000000 1975-01-01 82.03190000000000 1976-01-01 77.98690000000000 1977-01-01 76.20030000000000 1978-01-01 78.36550000000000 1979-01-01 76.62150000000000 1980-01-01 71.94390000000000 1981-01-01 67.26670000000000 1982-01-01 63.65060000000000 1983-01-01 64.28570000000000 1984-01-01 67.67100000000000 1985-01-01 80.86230000000000 1986-01-01 93.56710000000000 1987-01-01 95.89780000000000 1988-01-01 98.57480000000000 1989-01-01 98.41070000000000 1990-01-01 97.98240000000000 1991-01-01 97.13770000000000 1992-01-01 97.34750000000000 1993-01-01 97.88420000000000 1994-01-01 96.07820000000000 1995-01-01 95.48810000000000 1996-01-01 95.61360000000000 1997-01-01 95.44590000000000 1998-01-01 96.18840000000000 1999-01-01 96.54240000000000 2000-01-01 98.57830000000000 2001-01-01 99.12120000000000 2002-01-01 99.13940000000000 2003-01-01 99.19840000000000 2004-01-01 99.30150000000000 2005-01-01 99.49570000000000 2006-01-01 99.62920000000000 2007-01-01 99.75420000000000 2008-01-01 99.88010000000000 2009-01-01 99.91260000000000 2010-01-01 99.94600000000000 2011-01-01 99.97399999999999 2012-01-01 99.97980000000000 2013-01-01 99.98260000000000 2014-01-01 99.99130000000000 2015-01-01 99.99610000000000 2016-01-01 99.99740000000000