Year Percent 1993-01-01 3.1534200000000000 1994-01-01 3.0603300000000000 1995-01-01 2.5431600000000000 1996-01-01 2.3493100000000000 1997-01-01 2.0693799999999998 1998-01-01 2.1558400000000000 1999-01-01 2.1330500000000000 2000-01-01 1.9642000000000000 2001-01-01 1.7310700000000000 2002-01-01 1.6287300000000000 2003-01-01 1.4572900000000000 2004-01-01 1.3257700000000001 2005-01-01 1.1335400000000000 2006-01-01 0.9867680000000000 2007-01-01 0.8614090000000000 2008-01-01 0.7713909999999999 2009-01-01 0.6538740000000000 2010-01-01 0.6019000000000000 2011-01-01 0.5494000000000000 2012-01-01 0.5033460000000000 2013-01-01 0.4621070000000000 2014-01-01 0.5515120000000000 2015-01-01 0.5683699999999999 2016-01-01 0.5167340000000000