Year Percent 1984-01-01 71.9222 1985-01-01 74.9204 1986-01-01 73.6256 1987-01-01 63.6752 1988-01-01 59.5221 1989-01-01 57.5037 1990-01-01 56.3473 1991-01-01 50.8938 1992-01-01 50.1219 1993-01-01 59.7911 1994-01-01 66.8727 1995-01-01 63.5942 1996-01-01 61.0971 1997-01-01 62.4191 1998-01-01 58.7306 1999-01-01 51.9551 2000-01-01 48.4998 2001-01-01 42.7847 2002-01-01 36.0331 2003-01-01 31.2154 2004-01-01 29.3794 2005-01-01 30.8695 2006-01-01 30.7032 2007-01-01 34.0670 2008-01-01 43.4380 2009-01-01 48.1009 2010-01-01 51.0820 2011-01-01 55.5736 2012-01-01 55.3637 2013-01-01 56.9709 2014-01-01 65.5003 2015-01-01 77.6193 2016-01-01 82.9359