Number the elements in a list

[HanliePetoors]

Hi,

I'm working in ArcGIS Enterprise 11.1.

I would like to dynamically number the elements in a list so that when the list changes, the numbers change. The list is empty until a value is selected from a category selector, so its items change all the time.

I want to go from this:

to something like this:

I assume it's done with advanced formatting but I don't know where to start. How do I reference the items currently in the list in Arcade? And do I need to order them again by the percentage before I add the rank number?

Thanks

Hanlie