Year Percent 1996-01-01 21.350400000000000 1997-01-01 19.805999999999997 1998-01-01 20.796200000000000 1999-01-01 20.312500000000000 2000-01-01 20.379100000000000 2001-01-01 21.362200000000000 2002-01-01 21.022700000000000 2003-01-01 18.440900000000000 2004-01-01 22.077900000000000 2005-01-01 22.978700000000000 2006-01-01 24.290600000000000 2007-01-01 30.872500000000000 2008-01-01 28.308100000000000 2009-01-01 32.223800000000000 2010-01-01 35.575800000000000 2011-01-01 35.135600000000000 2012-01-01 35.419000000000004 2013-01-01 36.488900000000000 2014-01-01 34.736100000000000