Year Percent 1997-01-01 0.48099300000000000 1998-01-01 0.47331599999999996 1999-01-01 0.46398500000000004 2000-01-01 0.56495200000000000 2001-01-01 0.76725900000000000 2002-01-01 0.40708300000000000 2003-01-01 0.38109499999999996 2004-01-01 0.42228400000000000 2005-01-01 0.15536600000000000 2006-01-01 0.16533200000000000 2007-01-01 0.20550700000000002 2008-01-01 0.31479000000000000 2009-01-01 0.20884699999999998 2010-01-01 0.25044299999999997 2011-01-01 0.26193200000000000 2012-01-01 0.37002500000000000 2013-01-01 0.38804900000000000 2014-01-01 0.37013100000000000 2015-01-01 0.58081300000000000