TSVB two Counts division

Can you help me?
How can I draw the line that count2/count1 in this TSVB?

Hi @Aaron_Yu,
Welcome to the community!
If you're using the newest version of the Kibana (7.14), I'd recommend you to take a look at lens. It's very easy to achieve this result with the new formula feature.

But if you want to (or have to) stick to TSVB, use filter ratio: