Year Percent 1980-01-01 0.24702399999999997 1981-01-01 0.24168200000000000 1982-01-01 0.23225100000000000 1983-01-01 0.22019499999999997 1984-01-01 0.41975600000000000 1985-01-01 0.40941600000000000 1986-01-01 0.49779600000000000 1987-01-01 0.40804700000000000 1988-01-01 0.60795400000000000 1989-01-01 0.32089300000000000 1990-01-01 0.43672500000000000 1991-01-01 0.27790600000000000 1992-01-01 0.37946700000000000 1993-01-01 0.36129400000000000 1994-01-01 1.99610999999999980 1995-01-01 1.17456000000000000 1996-01-01 1.38211000000000000 1997-01-01 1.13673000000000000 1998-01-01 0.69419900000000000 1999-01-01 0.65954399999999990 2000-01-01 0.84844100000000000 2001-01-01 2.33855000000000000 2002-01-01 2.51675000000000000 2003-01-01 3.01078000000000000 2004-01-01 2.87877000000000030 2005-01-01 4.29125000000000000 2006-01-01 3.73858000000000020 2007-01-01 4.00104000000000000 2008-01-01 3.09429000000000000 2009-01-01 3.29395999999999980 2010-01-01 3.15449000000000000 2011-01-01 3.55409000000000000 2012-01-01 3.15355000000000000 2013-01-01 4.21854000000000000 2014-01-01 6.34863000000000000 2015-01-01 6.69080000000000000 2016-01-01 8.27191000000000000