Year Percent 1975-01-01 87.7473 1976-01-01 51.7466 1977-01-01 43.9555 1978-01-01 39.5028 1979-01-01 35.9459 1980-01-01 34.3443 1981-01-01 35.3699 1982-01-01 36.8644 1983-01-01 40.0850 1984-01-01 39.5475 1985-01-01 36.6153 1986-01-01 34.8596 1987-01-01 38.6238 1988-01-01 41.1493 1989-01-01 42.9506 1990-01-01 44.4962 1991-01-01 47.0932 1992-01-01 51.4255 1993-01-01 52.3574 1994-01-01 51.6405 1995-01-01 60.4562 1996-01-01 59.6456 1997-01-01 59.4420 1998-01-01 59.5453 1999-01-01 68.1222 2000-01-01 72.3930 2001-01-01 79.9086 2002-01-01 83.0744 2003-01-01 87.2144 2004-01-01 89.3825 2005-01-01 85.8548 2006-01-01 84.0144 2007-01-01 81.8525 2008-01-01 86.3435 2009-01-01 91.0830 2010-01-01 92.3102 2011-01-01 94.2252 2012-01-01 91.3402 2013-01-01 94.1917 2014-01-01 88.5379 2015-01-01 85.7435 2016-01-01 81.4553