Year Percent 1980-01-01 0.7710840000000000 1981-01-01 1.1787400000000000 1982-01-01 1.2411600000000000 1983-01-01 1.2316799999999999 1984-01-01 1.0101200000000001 1985-01-01 1.0101200000000001 1986-01-01 1.0101200000000001 1987-01-01 1.0101200000000001 1988-01-01 1.0101200000000001 1989-01-01 1.0101200000000001 1990-01-01 1.0101200000000001 1991-01-01 1.0101200000000001 1992-01-01 1.0101200000000001 1993-01-01 1.0101200000000001 1994-01-01 5.0656700000000000 1995-01-01 4.5562000000000000 1996-01-01 4.1984500000000000 1997-01-01 3.7141000000000000 1998-01-01 1.4008600000000000 1999-01-01 3.3568000000000000 2000-01-01 4.8141700000000000 2001-01-01 6.0439200000000000 2002-01-01 7.2498500000000000 2003-01-01 8.3182600000000000 2004-01-01 8.9418400000000000 2005-01-01 8.2836600000000010 2006-01-01 7.4494500000000000 2007-01-01 6.2127700000000000 2008-01-01 4.7871000000000000 2009-01-01 4.0080300000000010 2010-01-01 3.2816000000000000 2011-01-01 2.3177900000000000 2012-01-01 3.6875199999999997 2013-01-01 4.9951000000000000 2014-01-01 6.3399900000000000 2015-01-01 7.7824399999999990 2016-01-01 7.3730600000000010