Year Percent 1991-01-01 47.9650001525879 1992-01-01 50.2900009155273 1993-01-01 46.1759986877441 1994-01-01 47.2369995117188 1995-01-01 43.7039985656738 1996-01-01 47.8829994201660 1997-01-01 45.2540016174316 1998-01-01 41.5579986572266 1999-01-01 54.0200004577637 2000-01-01 56.7120018005371 2001-01-01 52.2659988403320 2002-01-01 47.2480010986328 2003-01-01 49.8819999694824 2004-01-01 43.9879989624023 2005-01-01 44.1660003662109 2006-01-01 45.3950004577637 2007-01-01 45.1090011596680 2008-01-01 44.3440017700195 2009-01-01 44.7389984130859 2010-01-01 50.1629981994629 2011-01-01 48.2270011901855 2012-01-01 51.2280006408691 2013-01-01 49.9230003356934 2014-01-01 49.7729988098145 2015-01-01 48.3359985351563 2016-01-01 47.9150009155273 2017-01-01 48.3540000915527