Year Percent 1990-01-01 2.2338299999999998 1991-01-01 2.2976099999999997 1992-01-01 2.3604200000000000 1993-01-01 2.3974500000000000 1994-01-01 2.3959700000000000 1995-01-01 2.4355300000000000 1996-01-01 2.3044599999999997 1997-01-01 2.2234400000000000 1998-01-01 2.1627700000000000 1999-01-01 2.1446600000000000 2000-01-01 2.1008500000000000 2001-01-01 2.1412299999999997 2002-01-01 2.2368200000000003 2003-01-01 2.3765200000000000 2004-01-01 2.3782200000000002 2005-01-01 2.3383200000000000 2006-01-01 2.2619700000000003 2007-01-01 2.1234599999999997 2008-01-01 2.0661000000000000 2009-01-01 2.1571700000000003 2010-01-01 2.1587400000000003 2011-01-01 2.1145099999999997 2012-01-01 2.1531599999999997 2013-01-01 2.1406200000000000 2014-01-01 2.1081600000000000 2015-01-01 1.9731599999999998 2016-01-01 2.0690700000000000