First published by Money Metals here: https://www.moneymetals.com/news/2018/02/16/us-dollar-gold-2018-001420

The Dollar Index dropped from 102.28 on December 30, 2016 to 91.82 on December 29, 2017, and further to 88.26 on January 25, 2018. The Index tracks the floating value of various unbacked fiat currencies against other fiat currencies also backed by nothing but debt, politician promises and taxing authority.