Year Percent 1990-01-01 3.4099800000000005 1991-01-01 3.0642800000000000 1992-01-01 2.6617700000000000 1993-01-01 2.5020900000000000 1994-01-01 2.2767300000000000 1995-01-01 2.1232500000000000 1996-01-01 2.2145799999999998 1997-01-01 2.2152500000000000 1998-01-01 2.0341600000000000 1999-01-01 2.3744200000000000 2000-01-01 2.6183200000000000 2001-01-01 2.7225400000000000 2002-01-01 2.3905300000000000 2003-01-01 2.4684100000000000 2004-01-01 2.4106200000000000 2005-01-01 2.1656000000000000 2006-01-01 1.8868400000000000 2007-01-01 2.0792800000000000 2008-01-01 2.3176700000000000 2009-01-01 2.1622900000000000 2010-01-01 2.3051900000000000 2011-01-01 2.2240400000000000 2012-01-01 2.5337800000000000 2013-01-01 2.5223000000000000 2014-01-01 2.4733600000000000 2015-01-01 2.8900799999999998 2016-01-01 3.1675900000000000