I agree with the previous comments, you won’t be able to do this calculation inside of Hubspot.
If this is a large pain point for your organization you should check out the company I work for, Rekener. Our software pulls out your Hubspot data and allows you to run analytics like the report you mentioned. I work on the solutions team and have built this type of report for customers before, feel free to ping me if you are interested!
Best,
Mike