Add Comparison Type: % of row (In Discover)

I would love a comparison type that calculates the 'percent of row'. This would be helpful when comparing semgents to a 'total' in colum-by-colm comparisons. Please see attached screen shot.In this examplle, it would be easy to spot growth and decline for specific segments. Currently, I can calculate the difference between rows A and B, but I am unable to calculate what % of the total is attributed to a segment. 

In order to do that now, I have to pull the data into Excel and calaulate the percentages. Adding this capability to Discover would allow me to set these reports and automate them for analysts.