Year Percent 1998-01-01 2.600000 1999-01-01 1.700000 2000-01-01 1.600000 2001-01-01 1.500000 2002-01-01 1.400000 2003-01-01 1.900000 2004-01-01 1.100000 2005-01-01 0.800000 2006-01-01 0.800000 2007-01-01 0.100000 2008-01-01 0.500000 2009-01-01 0.800000 2010-01-01 0.783563 2011-01-01 0.654055 2012-01-01 0.700062 2013-01-01 0.614388 2014-01-01 1.238370 2015-01-01 1.165110 2016-01-01 1.039350