Year Percent 1990-01-01 15.7839 1991-01-01 12.9882 1992-01-01 13.9115 1993-01-01 15.2496 1994-01-01 14.4972 1995-01-01 13.0133 1996-01-01 11.8615 1997-01-01 8.5642 1998-01-01 14.1465 1999-01-01 21.3057 2000-01-01 20.7284 2001-01-01 22.9480 2002-01-01 13.5318 2003-01-01 16.6852 2004-01-01 22.6056 2005-01-01 24.7299 2006-01-01 28.1449 2007-01-01 26.5466 2008-01-01 22.0950 2009-01-01 32.5390 2010-01-01 30.5049 2011-01-01 29.3393 2012-01-01 33.6731 2013-01-01 35.2112 2014-01-01 34.4043 2015-01-01 36.0319 2016-01-01 36.6051