Year Percent 1995-01-01 58.3081694562909 1996-01-01 58.2819367597673 1997-01-01 59.7072729930970 1998-01-01 58.8883288398656 1999-01-01 60.3860253668401 2000-01-01 60.6917838919208 2001-01-01 60.9156934074420 2002-01-01 63.1700101831201 2003-01-01 65.3784462300868 2004-01-01 65.9273259878138 2005-01-01 66.6769294332325 2006-01-01 66.1709234110044 2007-01-01 66.9807209661666 2008-01-01 66.8225532165764 2009-01-01 67.2623276819377 2010-01-01 67.9648144568280 2011-01-01 68.0879558709290 2012-01-01 68.5316270174528 2013-01-01 69.4022811497175 2014-01-01 69.6626893471690 2015-01-01 70.7194519322448 2016-01-01 71.4066623165002 2017-01-01 71.0458657213423