Year Percent 1990-01-01 18.1461000000000000 1991-01-01 16.8197000000000000 1992-01-01 15.0152000000000000 1993-01-01 16.0348000000000000 1994-01-01 16.9944000000000000 1995-01-01 16.9158000000000000 1996-01-01 17.4584000000000000 1997-01-01 17.2317000000000000 1998-01-01 0.7837729999999999 1999-01-01 0.9333250000000000 2000-01-01 0.8412390000000000 2001-01-01 1.0543000000000000 2002-01-01 1.3762299999999998 2003-01-01 1.2705799999999998 2004-01-01 2.3401000000000000 2005-01-01 3.0503600000000000 2006-01-01 2.2550500000000000 2007-01-01 2.6019900000000002 2008-01-01 2.2218000000000000 2009-01-01 2.0113600000000000 2010-01-01 1.5771000000000000 2011-01-01 26.1595000000000000 2012-01-01 30.9743000000000000 2013-01-01 31.2309999999999980 2014-01-01 32.5319000000000000 2015-01-01 29.8917000000000000 2016-01-01 33.4228000000000000