Help with Kibana displaying percentage by group

Hi!
I'd like to visualize my data in a certain way with Kibana and I don't know if it is possible or how to do it. I'd appreciate any help because I'm new to Kibana. I've attached a screenshot covering my current and, of course, invalid way of trying to achieve it with Filter Ratios.
Basically I have a field named action in my json which can currently have two different values: startSession or startVideoStreaming. I have a field called mediaSessionId which is a session GUID. In the example that can be seen on the screenshot I have 3 entries, 1 entry with sessionId 1 that has the action type of startSession, and 2 entries of sessionId 2, 1 with startSession action and 1 with startVideoStreaming. I'd love to see the following percentages:
startSession: 100%
startVideoStreaming: 50%
Basically I'd like something like this: (count of some action / count of unique mediaSessionIds). Thanks!

Your approach would work, but I think you need to change the actual query text because it's using Lucene syntax. Try _exists_:title instead of title:*- the asterisk approach is what we support with KQL, but this section doesn't use it.