Year Ratio 1971-01-01 1.044409990310670 1972-01-01 0.990930020809174 1973-01-01 0.961809992790222 1974-01-01 0.948780000209808 1975-01-01 0.984549999237061 1976-01-01 1.076460003852840 1977-01-01 1.065179944038390 1978-01-01 1.067729949951170 1979-01-01 1.070809960365300 1980-01-01 1.058439970016480 1987-01-01 1.047129988670350 1988-01-01 1.046779990196230 1989-01-01 1.044420003890990 1990-01-01 1.043009996414180 1998-01-01 1.044170022010800 2008-01-01 0.970040023326874 2009-01-01 0.969139993190765 2010-01-01 0.967899978160858 2011-01-01 0.967249989509583 2012-01-01 0.964810013771057 2013-01-01 0.975619971752167 2014-01-01 0.981689989566803 2015-01-01 0.985679984092712 2016-01-01 0.984019994735718