Year Percent 1992-01-01 61.58730000000000 1993-01-01 63.17160000000000 1994-01-01 66.51260000000000 1995-01-01 55.04110000000000 1996-01-01 51.97410000000000 1997-01-01 54.52000000000000 1998-01-01 48.17870000000000 1999-01-01 41.51510000000000 2000-01-01 45.93250000000000 2001-01-01 55.54610000000000 2002-01-01 65.52240000000000 2003-01-01 75.23610000000000 2004-01-01 81.77060000000000 2005-01-01 89.39160000000000 2006-01-01 95.13510000000000 2007-01-01 97.22950000000000 2008-01-01 97.31380000000000 2009-01-01 94.95200000000001 2010-01-01 92.28299999999999 2011-01-01 91.16360000000000 2012-01-01 89.50020000000000 2013-01-01 87.84700000000001 2014-01-01 82.30290000000000 2015-01-01 75.60000000000000 2016-01-01 74.83310000000000