Year Percent 1991-01-01 60.530400000000000 1992-01-01 68.288500000000000 1993-01-01 61.170000000000000 1994-01-01 48.321900000000000 1995-01-01 31.762800000000000 1996-01-01 33.898700000000000 1997-01-01 19.970500000000000 1998-01-01 7.778910000000001 1999-01-01 10.417800000000000 2000-01-01 11.130900000000000 2001-01-01 12.575500000000000 2002-01-01 16.009100000000000 2003-01-01 21.228700000000000 2004-01-01 28.511000000000000 2005-01-01 34.705800000000000 2006-01-01 39.290700000000000 2007-01-01 47.123600000000000 2008-01-01 60.650900000000000 2009-01-01 68.653100000000000 2010-01-01 67.887100000000000 2011-01-01 64.744900000000000 2012-01-01 65.413900000000000 2013-01-01 65.964700000000000 2014-01-01 61.976800000000000 2015-01-01 55.810600000000000 2016-01-01 52.080600000000000