Year Percent 1988-01-01 0.9120860000000001 1989-01-01 0.5630020000000000 1990-01-01 0.4099000000000000 1991-01-01 0.4536900000000000 1992-01-01 0.5891529999999999 1993-01-01 0.6332300000000001 1994-01-01 0.7073530000000000 1995-01-01 0.7218790000000000 1996-01-01 0.7395910000000000 1997-01-01 0.7447380000000000 1998-01-01 1.9408500000000000 1999-01-01 2.6795100000000000 2000-01-01 2.1668400000000000 2001-01-01 2.5563800000000000 2002-01-01 4.2399500000000000 2003-01-01 4.8545000000000000 2004-01-01 5.2153199999999990 2005-01-01 3.3911000000000000 2006-01-01 4.3119300000000000 2007-01-01 6.1826000000000000 2008-01-01 5.7202699999999990 2009-01-01 5.9083800000000000 2010-01-01 5.3948400000000000 2011-01-01 4.7399300000000000 2012-01-01 4.6101900000000000 2013-01-01 6.0994699999999990 2014-01-01 8.7725300000000000 2015-01-01 8.1076699999999990 2016-01-01 4.7896000000000000 2017-01-01 7.6883899999999990