Year Percent 1999-01-01 1.80410723228422 2000-01-01 1.71260481574914 2001-01-01 1.74715482813598 2002-01-01 1.93519935962483 2003-01-01 2.12350280481991 2004-01-01 2.41895516059246 2005-01-01 2.56210864424875 2006-01-01 2.39839131480698 2007-01-01 2.26551067403330 2008-01-01 1.97426926727647 2009-01-01 2.48103231947208 2010-01-01 2.27810392112766 2011-01-01 2.15978771262220 2012-01-01 2.26999136584435 2013-01-01 2.57559372794469