Need help to report related cumulative figures
I have made myself a little proof-of-concept fmp12 file to try to work out something I don't totally understand how to do. The db is based on a simple relationship between two tables ("Work List" and "Contributors") using an IDkey field that generates a serial number and I use a portal in the main data entry table ("Work List") to add multiple related records for each local record, which is called a "work". The purpose is to be able to enter contributors of a work (let's say, a piece of music) and to enter what percentage of the total time for each work is theirs. The db then calculates how much of the work's time is divided to each contributor for payment purposes.
The db so far works fine. What I need to learn is how to make the footer display a list of every contributor (dynamically, via a portal I should think) and to display a percentage representing their TOTAL CONTRIBUTION to all works (records). I need the db to somehow sum all time for each contributor, by finding each of their related records, and calculate a percentage of the overall time.
In other words, if there are 3 works, 4 contributors and a total time of 9:36, I want the footer to show each person and their total percentage of contribution overall.
Here's how I'd like it to look in the footer:
The db is available from this link: https://www.dropbox.com/s/kr61jytaswvlgmr/PercentageTimeWIP.fmp12
Any help is greatly appreciated! Screenshots: