Year Percent 1992-01-01 0.178952 1993-01-01 1.339500 1994-01-01 2.382930 1995-01-01 2.978100 1996-01-01 3.877540 1997-01-01 5.964250 1998-01-01 9.252530 1999-01-01 13.918500 2000-01-01 17.135200 2001-01-01 15.693500 2002-01-01 13.776200 2003-01-01 15.341800 2004-01-01 21.520000 2005-01-01 28.408300 2006-01-01 35.855800 2007-01-01 44.063800 2008-01-01 31.734200 2009-01-01 25.239500 2010-01-01 36.226100 2011-01-01 31.739000 2012-01-01 30.452300 2013-01-01 37.000500 2014-01-01 34.377700 2015-01-01 29.293700 2016-01-01 28.510900 2017-01-01 32.914500