Year Percent 1980-01-01 0.00025499999999999996 1981-01-01 2.37685000000000000000 1982-01-01 5.64246000000000000000 1983-01-01 4.90344000000000000000 1984-01-01 2.21520000000000000000 1985-01-01 2.15793000000000000000 1986-01-01 3.86480000000000000000 1987-01-01 6.46700000000000050000 1988-01-01 13.87730000000000000000 1989-01-01 18.96270000000000000000 1990-01-01 16.57510000000000000000 1991-01-01 20.58320000000000000000 1992-01-01 15.49720000000000000000 1993-01-01 6.74909000000000000000 1994-01-01 7.55793999999999900000 1995-01-01 7.05726000000000000000 1996-01-01 7.35563000000000100000 1997-01-01 7.35563000000000100000 1998-01-01 2.81833000000000000000 1999-01-01 2.02774000000000000000 2000-01-01 1.96075999999999980000 2001-01-01 2.36065000000000000000 2002-01-01 2.85340000000000000000 2003-01-01 2.27464000000000000000 2004-01-01 2.20985000000000000000 2005-01-01 2.25670000000000000000 2006-01-01 2.22509000000000020000 2007-01-01 2.05488000000000000000 2008-01-01 2.60534000000000000000 2009-01-01 2.09885999999999970000 2010-01-01 0.81177000000000000000 2011-01-01 1.00315000000000000000 2012-01-01 1.71662999999999990000 2013-01-01 2.73324000000000030000 2014-01-01 3.23381000000000000000 2015-01-01 3.36889000000000000000 2016-01-01 3.54055000000000000000