Year Ratio 1979-01-01 0.611220002174377 2005-01-01 0.984899997711182 2007-01-01 0.978670001029968 2008-01-01 0.976000010967255 2009-01-01 0.974969983100891 2010-01-01 0.991599977016449 2011-01-01 0.994960010051727 2012-01-01 1.004500031471250 2013-01-01 0.974470019340515 2014-01-01 0.970309972763062 2015-01-01 1.007539987564090 2016-01-01 0.982339978218079