Year Percent 1990-01-01 2.1834000000000000 1991-01-01 2.1599600000000000 1992-01-01 2.6464800000000000 1993-01-01 2.8996400000000000 1994-01-01 2.6339000000000000 1995-01-01 2.3065200000000000 1996-01-01 2.4852000000000000 1997-01-01 2.4942000000000000 1998-01-01 2.4479400000000000 1999-01-01 2.3698400000000000 2000-01-01 2.2953400000000000 2001-01-01 2.4880700000000000 2002-01-01 2.4505900000000000 2003-01-01 2.4231900000000000 2004-01-01 2.5359000000000000 2005-01-01 2.8880800000000000 2006-01-01 4.1322900000000000 2007-01-01 3.6811800000000003 2008-01-01 1.7135099999999999 2009-01-01 1.7919200000000002 2010-01-01 1.7475900000000002 2011-01-01 1.6820099999999998 2012-01-01 1.7141000000000000 2013-01-01 1.8468400000000000 2014-01-01 1.6108500000000000 2015-01-01 1.5030700000000001