Year Percent 1996-01-01 7.8684899999999995 1997-01-01 12.0788000000000000 1998-01-01 14.2931000000000000 1999-01-01 12.8224000000000000 2000-01-01 10.6423000000000000 2001-01-01 12.8909999999999980 2002-01-01 13.0619000000000000 2003-01-01 15.9056000000000000 2004-01-01 17.3751000000000000 2005-01-01 15.1035000000000000 2006-01-01 15.1263000000000000 2007-01-01 13.8509999999999990 2008-01-01 16.5549000000000000 2009-01-01 18.1601000000000000 2010-01-01 18.8577000000000000 2011-01-01 21.5528000000000000 2012-01-01 18.2443000000000000 2013-01-01 18.4360000000000000 2014-01-01 20.3869000000000000