Year Percent 1990-01-01 51.1721000000000000 1991-01-01 54.8214000000000000 1992-01-01 52.1889000000000000 1993-01-01 52.1502000000000000 1994-01-01 54.1765000000000000 1995-01-01 52.9665000000000000 1996-01-01 52.2359000000000000 1997-01-01 48.1741000000000000 1998-01-01 45.5594000000000000 1999-01-01 44.1765000000000000 2000-01-01 39.2285000000000000 2001-01-01 3.2497500000000000 2002-01-01 3.3772800000000003 2003-01-01 2.1696800000000000 2004-01-01 2.4888200000000000 2005-01-01 2.0516600000000000 2006-01-01 2.3071599999999997 2007-01-01 3.0315100000000000 2008-01-01 10.4585000000000000 2009-01-01 15.0088000000000000 2010-01-01 49.5372000000000000 2011-01-01 45.5545000000000000 2012-01-01 49.8353000000000000 2013-01-01 47.8600000000000000 2014-01-01 42.9632000000000000 2015-01-01 49.2947000000000000 2016-01-01 48.2048000000000000