Help needed with a % connection path KPI

I am trying to figure out how i can make a connection KPI which shows the path percentage of cases that passed through. now i want to see the path percentage flow from each individual Activity. exmaple: Start -->Activity A (branches pathways) ---55% for a path---> Activity B (branches Pathways) --23% for a path--> activity Z. so from each Acitivy i want to calculate how much of the (total) cases that landed there go a certain path % wise.

Now i figured out by doing: COUNT (DISTINCT SOURCE ("Table"."colum")) / GLOBAL(COUNT (DISTINCT SOURCE ("Table"."colum"))) I can filter the path connections to % based on the Total amount of cases present in the dataset.

This only shows me how cases % wise flow through the whole process. but not from an indivual activity.

In my mind somehow every Activity point needs to be seen as the "new" total 100% so a calculation can be made for the paths. but i cannot figured that out.

exmaple:

Start (100 cases) Branches to Acitivity A (50 cases) and B(50 cases) Both pathways would show 50% on the path connection. Lets go further on A: A 50 cases splits to activity D (30 cases) and K (20 cases). Now the pathway to D should show 60% (=30/50) and K 40% (=20/50). etc. etc. etc.