Comparing relative change for different base value
https://en.wikipedia.org/wiki/Relative_change_and_difference
Törnqvist, Leo; Vartia, Pentti; Vartia, Yrjö (1985), &quot;How Should Relative Changes Be Measured?&quot;, The American Statistician, 39 (1): 43–46, doi:10.2307/2683905