Year Percent 1980-01-01 2.07845999999999980 1981-01-01 2.42500000000000000 1982-01-01 2.39378000000000000 1983-01-01 1.97423000000000000 1984-01-01 1.48498000000000000 1985-01-01 1.97648000000000000 1986-01-01 1.92340999999999980 1987-01-01 1.52461000000000000 1988-01-01 0.94048500000000000 1989-01-01 0.75279900000000000 1990-01-01 0.40290200000000000 1991-01-01 0.35809000000000000 1992-01-01 0.37671300000000000 1993-01-01 0.42211800000000005 1994-01-01 0.32019600000000000 1995-01-01 0.16472400000000000 1996-01-01 0.58404500000000000 1997-01-01 1.50090000000000000 1998-01-01 2.12314000000000020 1999-01-01 3.44929000000000000 2000-01-01 4.26218000000000000 2001-01-01 5.18901999999999900 2002-01-01 6.26354000000000000 2003-01-01 6.69138999999999900 2004-01-01 6.67203000000000000 2005-01-01 5.36158000000000000 2006-01-01 5.38814000000000000 2007-01-01 4.13543000000000000 2008-01-01 4.41801999999999900 2009-01-01 4.14809000000000000 2010-01-01 4.29859000000000000 2011-01-01 5.64494000000000000 2012-01-01 8.33215000000000000 2013-01-01 6.70689000000000000 2014-01-01 7.83658999999999900 2015-01-01 10.64150000000000000 2016-01-01 16.67290000000000000