Year Percent 1991-01-01 2.6878000000000000 1992-01-01 2.8148200000000000 1993-01-01 2.8444900000000000 1994-01-01 3.0178100000000000 1995-01-01 2.6720900000000003 1996-01-01 2.3708099999999996 1997-01-01 2.2005800000000000 1998-01-01 2.3352700000000000 1999-01-01 2.3094300000000000 2000-01-01 2.3540799999999997 2001-01-01 2.3235200000000003 2002-01-01 2.6371599999999997 2003-01-01 2.7097200000000000 2004-01-01 2.6038400000000000 2005-01-01 2.4153700000000002 2006-01-01 1.8590000000000000 2007-01-01 1.7207900000000000 2008-01-01 1.7947500000000000 2009-01-01 1.9536700000000000 2010-01-01 1.8681200000000000 2011-01-01 1.7976700000000000 2012-01-01 1.7884300000000000 2013-01-01 1.8129900000000000 2014-01-01 1.8223099999999999 2015-01-01 1.8798800000000000 2016-01-01 1.9074200000000001