Year Percent 1990-01-01 0.8129330000000000 1991-01-01 0.7805900000000000 1992-01-01 1.2884200000000001 1993-01-01 2.7048200000000002 1994-01-01 3.4105900000000000 1995-01-01 2.8056600000000000 1996-01-01 4.0229000000000000 1997-01-01 6.2594400000000010 1998-01-01 7.8375000000000000 1999-01-01 6.4636000000000000 2000-01-01 7.5639800000000000 2001-01-01 7.0410500000000000 2002-01-01 6.1518100000000000 2003-01-01 4.5174600000000000 2004-01-01 3.5096900000000000 2005-01-01 3.7005199999999996 2006-01-01 4.4356599999999995 2007-01-01 6.0520500000000000 2008-01-01 7.9571800000000000 2009-01-01 9.3762700000000000 2010-01-01 11.0482000000000000 2011-01-01 14.7072000000000000 2012-01-01 17.6309000000000000 2013-01-01 16.9803000000000000 2014-01-01 17.8578000000000000 2015-01-01 16.8147000000000000 2016-01-01 16.4505000000000000