Year Percent 1965-01-01 92.8024 1966-01-01 90.8812 1967-01-01 96.4821 1968-01-01 96.9363 1969-01-01 96.8047 1970-01-01 91.2457 1971-01-01 80.9500 1972-01-01 78.9023 1973-01-01 91.5832 1974-01-01 98.6034 1975-01-01 98.4647 1976-01-01 95.1326 1977-01-01 81.0753 1978-01-01 79.3374 1979-01-01 74.9332 1980-01-01 77.2257 1981-01-01 74.6282 1982-01-01 70.1289 1983-01-01 71.2783 1984-01-01 66.7396 1985-01-01 64.9903 1986-01-01 72.0512 1987-01-01 91.0266 1988-01-01 89.8545 1989-01-01 93.3079 1990-01-01 94.4329 1991-01-01 91.9611 1992-01-01 73.2981 1993-01-01 61.3677 1994-01-01 62.1191 1995-01-01 64.1316 1996-01-01 69.5206 1997-01-01 74.2923 1998-01-01 78.2068 1999-01-01 80.7090 2000-01-01 83.9390 2001-01-01 87.0067 2002-01-01 85.8322 2003-01-01 74.7278 2004-01-01 67.1065 2005-01-01 70.8078 2006-01-01 83.1634 2007-01-01 92.8428 2008-01-01 94.1258 2009-01-01 96.0236 2010-01-01 88.8243 2011-01-01 82.7546 2012-01-01 82.7429 2013-01-01 78.3072 2014-01-01 70.9366