Trying to figure out how to get data (ideally aggregate) on card activity dates

[Barnaby Page]

I have a board for team workflow tracking. Cards are moved from one list to another as they progress through workflow stages. Eventually, they all end up in a "finished" list and stay there. So, pretty standard setup.

What I want to do is get data on the days between creation of a card and moving to the "finished" list. I hoped that CSV export might provide all the card activity dates, in which case I could easily extract the data in Excel, but it doesn't seem to.

My ultimate goal is to get the average days for all cards created in a given period, but having just the numbers for individual cards would be a good start.

Maybe there's a Power-Up that could do something like this?