Year Percent 1980-01-01 0.89598300000000000 1981-01-01 0.88064000000000000 1982-01-01 0.96138300000000000 1983-01-01 1.19282000000000000 1984-01-01 1.14198000000000000 1985-01-01 1.31318999999999990 1986-01-01 0.58405800000000000 1987-01-01 0.56464799999999990 1988-01-01 0.48385300000000000 1989-01-01 0.37442800000000004 1990-01-01 0.20055300000000000 1991-01-01 0.77332800000000000 1992-01-01 0.77207799999999990 1993-01-01 1.77004000000000000 1994-01-01 1.38168999999999990 1995-01-01 0.97408300000000000 1996-01-01 2.21245999999999960 1997-01-01 3.21377000000000020 1998-01-01 4.15383000000000000 1999-01-01 6.34464000000000000 2000-01-01 6.69937000000000000 2001-01-01 9.75021000000000100 2002-01-01 12.77410000000000000 2003-01-01 13.20120000000000000 2004-01-01 10.63830000000000000 2005-01-01 8.57298999999999900 2006-01-01 6.91831000000000100 2007-01-01 5.71812000000000000 2008-01-01 5.44756000000000000 2009-01-01 6.53308000000000000 2010-01-01 7.18360000000000000 2011-01-01 7.83233000000000100 2012-01-01 9.62563999999999900 2013-01-01 12.58220000000000000 2014-01-01 17.31540000000000000 2015-01-01 21.41540000000000000 2016-01-01 22.56780000000000000