Year Percent 1985-01-01 34.0116 1986-01-01 50.3591 1987-01-01 53.1169 1988-01-01 32.8652 1989-01-01 29.5941 1990-01-01 25.0163 1991-01-01 26.4144 1992-01-01 34.6851 1993-01-01 44.6129 1994-01-01 50.3623 1995-01-01 47.8005 1996-01-01 50.9200 1997-01-01 49.4952 1998-01-01 44.8844 1999-01-01 44.9018 2000-01-01 40.8610 2001-01-01 33.1518 2002-01-01 32.2477 2003-01-01 33.9854 2004-01-01 38.6796 2005-01-01 37.9116 2006-01-01 37.0850 2007-01-01 35.9715 2008-01-01 26.5332 2009-01-01 23.5596 2010-01-01 28.8538 2011-01-01 27.3906 2012-01-01 27.8717 2013-01-01 31.3615 2014-01-01 35.2037 2015-01-01 38.6286 2016-01-01 40.7547