Joined List Date

Would definitely be a life saver!
My basic need :
I have a list called “MQL 700+” which contains the number of MQL’s with a Hubspot Score greater than 700. This is my main KPI to evaluate the performance of campaigns acquisition, as my lead scoring is pretty aggressive.
I would like to be able to identify the contacts that have been joining this list per month, so I could measure my perfomance over the year. Basic need, I told you. Sadly, still can’t do it right now.
Thanks.