Year Percent 1991-01-01 1.4372000000000000 1992-01-01 1.4799500000000000 1993-01-01 1.6646299999999998 1994-01-01 1.7767900000000000 1995-01-01 1.7771599999999999 1996-01-01 2.0144599999999997 1997-01-01 2.1589300000000000 1998-01-01 2.2504700000000000 1999-01-01 6.3876900000000000 2000-01-01 3.7917600000000000 2001-01-01 2.3244200000000000 2002-01-01 2.3275500000000000 2003-01-01 2.2499599999999997 2004-01-01 2.0909700000000000 2005-01-01 2.0073900000000000 2006-01-01 2.0026300000000000 2007-01-01 2.0553900000000000 2008-01-01 1.8183300000000000 2009-01-01 1.9172799999999999 2010-01-01 1.9668900000000002 2011-01-01 1.9737700000000000 2012-01-01 1.8406900000000002 2013-01-01 1.7614599999999998 2014-01-01 1.7367099999999998 2015-01-01 1.7628599999999999 2016-01-01 1.8393300000000000