Year Percent 1988-01-01 0.8643020000000000 1989-01-01 0.8302250000000000 1990-01-01 0.2649870000000000 1991-01-01 0.2739590000000000 1992-01-01 0.2304890000000000 1993-01-01 0.2755640000000000 1994-01-01 1.9982900000000001 1995-01-01 3.9604800000000004 1996-01-01 3.8623900000000000 1997-01-01 5.7805700000000000 1998-01-01 5.9852700000000000 1999-01-01 6.6619100000000010 2000-01-01 6.9167100000000010 2001-01-01 7.9217500000000000 2002-01-01 11.0370000000000000 2003-01-01 11.3113000000000000 2004-01-01 12.8112000000000000 2005-01-01 11.3599000000000000 2006-01-01 10.1853000000000000 2007-01-01 9.4798200000000000 2008-01-01 8.5639000000000000 2009-01-01 8.5083000000000000 2010-01-01 7.6288399999999990 2011-01-01 5.6521600000000000 2012-01-01 6.8981400000000000 2013-01-01 6.3395400000000000 2014-01-01 6.5354800000000010 2015-01-01 7.1570199999999990 2016-01-01 8.5526699999999990