Year Percent 1996-01-01 58.4606 1997-01-01 57.7554 1998-01-01 62.4392 1999-01-01 67.3054 2000-01-01 74.0589 2001-01-01 74.7615 2002-01-01 63.7211 2003-01-01 62.1247 2004-01-01 58.9209 2005-01-01 54.7265 2006-01-01 54.0694 2007-01-01 50.4344 2008-01-01 45.1220 2009-01-01 39.3376 2010-01-01 42.0463 2011-01-01 44.4649 2012-01-01 43.0091 2013-01-01 43.4402 2014-01-01 44.2568