Residence time

Hello, anyone knows how to generate residence time distribution graph in comsol ???

I set up final time= 2 seconds and 5000 particles. I defined Wall condition as dissapear at outlet: This graph seems to show the number of still present on my volume at each selected time.

I would like to generate RTD curve, but I cannot decipher how to do it in comsol :/

Thanks for any help you could give me, Jhoan