Year Percent 1963-01-01 93.49220000000000 1964-01-01 91.89140000000000 1965-01-01 91.59960000000000 1966-01-01 92.23490000000000 1967-01-01 94.05490000000000 1968-01-01 94.95110000000000 1969-01-01 95.59260000000000 1970-01-01 94.59480000000000 1971-01-01 93.69310000000000 1972-01-01 94.00790000000000 1973-01-01 93.73000000000000 1974-01-01 87.56560000000000 1975-01-01 82.02100000000000 1976-01-01 80.05550000000000 1977-01-01 81.31360000000000 1978-01-01 83.88910000000000 1979-01-01 84.83170000000000 1980-01-01 84.95100000000001 1981-01-01 83.61150000000000 1982-01-01 83.06840000000000 1983-01-01 83.65770000000000 1984-01-01 84.50020000000000 1985-01-01 84.08090000000000 1986-01-01 83.42830000000000 1987-01-01 83.27880000000000 1988-01-01 83.65810000000000 1989-01-01 85.00890000000000 1990-01-01 86.54000000000000 1991-01-01 88.22430000000000 1992-01-01 88.99270000000000 1993-01-01 88.82290000000000 1994-01-01 88.28100000000000 1995-01-01 87.85780000000000 1996-01-01 88.88260000000000 1997-01-01 89.83270000000000 1998-01-01 90.48050000000000 1999-01-01 93.86110000000000 2000-01-01 93.92990000000000 2001-01-01 93.57070000000000 2002-01-01 94.61750000000000 2003-01-01 95.43810000000000 2004-01-01 95.01940000000000 2005-01-01 94.74540000000000 2006-01-01 94.82200000000000 2007-01-01 95.58600000000000 2008-01-01 96.28670000000000 2009-01-01 96.38610000000000 2010-01-01 96.42610000000000 2011-01-01 96.25620000000000 2012-01-01 95.64940000000000 2013-01-01 95.19830000000000 2014-01-01 94.78550000000000 2015-01-01 92.90280000000000 2016-01-01 89.06190000000000