Year Percent 1991-01-01 15.5390000000000010 1992-01-01 15.1379000000000000 1993-01-01 23.3290000000000000 1994-01-01 28.5572000000000000 1995-01-01 30.6319999999999980 1996-01-01 27.0912000000000000 1997-01-01 22.7462000000000000 1998-01-01 24.0975000000000000 1999-01-01 19.7856000000000000 2000-01-01 15.2233000000000000 2001-01-01 11.9025000000000000 2002-01-01 9.0698400000000000 2003-01-01 5.4118900000000005 2004-01-01 3.1448700000000000 2005-01-01 3.5209000000000000 2006-01-01 7.2785600000000010 2007-01-01 8.2599400000000000 2008-01-01 8.5681100000000000 2009-01-01 10.7268000000000000 2010-01-01 9.0866000000000000 2011-01-01 7.5302500000000000 2012-01-01 9.5539100000000000 2013-01-01 10.0378000000000000 2014-01-01 8.9662700000000000 2015-01-01 8.9662700000000000 2016-01-01 7.9509000000000000