Year Percent 1994-01-01 32.65 1995-01-01 39.16 1996-01-01 45.39 1997-01-01 53.15 1998-01-01 57.29 1999-01-01 65.43 2000-01-01 67.98 2001-01-01 65.68 2002-01-01 63.08 2003-01-01 65.79 2004-01-01 77.52 2005-01-01 83.78 2006-01-01 83.55 2007-01-01 85.57 2008-01-01 79.70 2009-01-01 85.91 2010-01-01 88.64 2011-01-01 88.96 2012-01-01 90.66 2013-01-01 94.24 2014-01-01 97.95 2015-01-01 100.12