Year Number 2004-01-01 0.514502540356293 2005-01-01 0.530580744742427 2006-01-01 0.546658949128561 2007-01-01 0.562737153514695 2008-01-01 0.562737153514695 2009-01-01 0.546799614023802 2010-01-01 0.546272493573265 2011-01-01 0.530546623794212 2012-01-01 0.530717272434867 2013-01-01 0.562791445570027 2014-01-01 0.514552178806882