Year Percent 1980-01-01 1.2060300000000000 1981-01-01 1.1040700000000000 1982-01-01 3.0387800000000000 1983-01-01 6.2875600000000000 1984-01-01 8.4837200000000000 1985-01-01 15.6308000000000000 1986-01-01 18.9692000000000000 1987-01-01 18.8161000000000000 1988-01-01 16.2684000000000000 1989-01-01 14.4365000000000000 1990-01-01 13.3540000000000010 1991-01-01 12.2315000000000000 1992-01-01 8.1028000000000000 1993-01-01 5.3559500000000000 1994-01-01 3.0241900000000000 1995-01-01 2.1147800000000000 1996-01-01 1.5929000000000000 1997-01-01 1.3752400000000000 1998-01-01 1.2344600000000001 1999-01-01 2.2876600000000000 2000-01-01 2.8179700000000000 2001-01-01 3.8168500000000000 2002-01-01 4.3157200000000000 2003-01-01 3.5521000000000000 2004-01-01 3.1516599999999997 2005-01-01 2.2431900000000002 2006-01-01 1.9997200000000002 2007-01-01 1.6764299999999999 2008-01-01 1.4032400000000000 2009-01-01 0.8309790000000001 2010-01-01 1.1626299999999998 2011-01-01 1.3461299999999998 2012-01-01 1.2807700000000000 2013-01-01 1.3765100000000001 2014-01-01 1.3165900000000000 2015-01-01 1.5659600000000000 2016-01-01 1.6661200000000000