Year Percent 1996-01-01 1.3465200000000002 1997-01-01 1.8669600000000000 1998-01-01 1.5715600000000000 1999-01-01 2.0982000000000000 2000-01-01 2.4289500000000000 2001-01-01 2.8557500000000000 2002-01-01 3.1649400000000000 2003-01-01 3.8243500000000000 2004-01-01 3.2202599999999997 2005-01-01 2.7352300000000000 2006-01-01 2.8219700000000000 2007-01-01 3.0562000000000000 2008-01-01 2.8047400000000002 2009-01-01 2.2972799999999998 2010-01-01 2.4985800000000000 2011-01-01 3.0013400000000003 2012-01-01 2.7984000000000000 2013-01-01 3.8951700000000000 2014-01-01 3.9378400000000000 2015-01-01 3.5293099999999997 2016-01-01 3.4808800000000004