This data accompanies the paper “The Cryptocurrency Uncertainty Index” : Lucey, Brian M. and Vigne, Samuel and Yarovaya, Larisa and Wang, Yizhi, The Cryptocurrency Uncertainty Index (March 16, 2021). https://papers.ssrn.com/sol3/papers.cfm?abstract_id=3805891
Usage of this is free but requires that you cite the above paper.
NOTE: Updated data and commentary on this and other indices can be found at https://sites.google.com/view/cryptocurrency-indices/home?authuser=0