Ecommerce Attachment Rate

I'm trying to figure out if a customer bought X of the primary part on an order, what other parts did they buy and how many. This will help me determine which primary parts are selling on their own and which have other items attached to the order.

In the attached file, you'll see Part IDs-- the G parts are the primary parts.

What I'm seeking to report is something like this:

- 5 customers bought part G1
- of those 5, only 2 customers bought a 2nd item -- that second item is _____ part ID
- the results would show that there's a 40% attachment rate to part G1

I have a large set of data and I'm trying to automate this view/dashboard as the data refreshes.

I understand that the typical marketing attachment rate = (secondary products sold / primary products sold) * 100, but this isn't very useful for my business.

Help please!