Doss, Charles R., and Edward McFowland III. "Nonparametric Subset Scanning for Detection of Heteroscedasticity." Journal of Computational and Graphical Statistics 31, no. 3 (2022): 813–823.
Excel's PERCENTOF function returns the percentage that a subset of data contributes to a whole dataset, saving you from having to create additional or complex formulas to generate the same outcome.