Year Percent 1990-01-01 39.54 1991-01-01 41.90 1992-01-01 43.25 1993-01-01 49.65 1994-01-01 47.17 1995-01-01 52.52 1996-01-01 56.43 1997-01-01 56.69 1998-01-01 59.81 1999-01-01 64.55 2000-01-01 60.33 2001-01-01 56.43 2002-01-01 54.95 2003-01-01 62.72 2004-01-01 65.84 2005-01-01 66.47 2006-01-01 65.39 2007-01-01 71.52 2008-01-01 52.86 2009-01-01 73.22 2010-01-01 73.51 2011-01-01 68.95 2012-01-01 75.26 2013-01-01 75.64 2014-01-01 80.10 2015-01-01 84.22 2016-01-01 90.61