Is it possible to combine multiple fields into a weighted average in a Qualtrics dashboard?

Hi all
I'm running a brand tracking survey for a client where we ask prospective customers which brands they would consider for which services. The question looks like this (anonymised here of course):
We use the data from this to show a % of customers who would consider each brand for each service line; this looks like this:
However, we also want to show an overall consideration score for all service lines. The problem is that in the survey we only display service lines that are relevant for that particular customer, so rather than just averaging across all scores we would need to be able to weight each score by the base size for that service line. I haven't been able to find a way to do this in Qualtrics yet, and exporting everything to Excel to do it there is becoming increasingly time consuming as the project goes on. Does anyone know of a way to do this in Qualtrics?