Year Percent 1991-01-01 27.313200000000000 1992-01-01 19.662400000000000 1993-01-01 8.990400000000000 1994-01-01 10.535300000000000 1995-01-01 7.359330000000000 1996-01-01 9.421380000000001 1997-01-01 9.595060000000000 1998-01-01 10.771900000000000 1999-01-01 9.857470000000000 2000-01-01 10.632800000000000 2001-01-01 11.961600000000000 2002-01-01 15.621400000000000 2003-01-01 21.711600000000000 2004-01-01 23.501200000000000 2005-01-01 25.063200000000000 2006-01-01 24.630700000000000 2007-01-01 26.694900000000000 2008-01-01 22.592900000000000 2009-01-01 26.034000000000002 2010-01-01 35.286100000000000 2011-01-01 38.190600000000000 2012-01-01 39.015000000000000 2013-01-01 40.413200000000000 2014-01-01 42.165500000000000 2015-01-01 42.461500000000000 2016-01-01 44.126200000000000