Year Percent 1996-01-01 15.9973 1997-01-01 22.0661 1998-01-01 20.4906 1999-01-01 22.7046 2000-01-01 21.5015 2001-01-01 53.7523 2002-01-01 10.0152 2003-01-01 56.3311 2004-01-01 31.3125 2005-01-01 32.0416 2006-01-01 35.7918 2007-01-01 38.3426 2008-01-01 30.1631 2009-01-01 34.4446 2010-01-01 40.8826 2011-01-01 37.2208 2012-01-01 40.8780 2013-01-01 34.7202 2014-01-01 34.4761