. fair value of debt : at december 29 , 2018 , the aggregate fair value of our total debt was $ 30.1 billion as compared with a carrying value of $ 31.2 billion . at december 30 , 2017 , the aggregate fair value of our total debt was $ 33.0 billion as compared with a carrying value of $ 31.5 billion . our short-term debt and commercial paper had carrying values that approximated their fair values at december 29 , 2018 and december 30 , 2017