I'm trying to create a report that answers the question: When was this potential updated to its current stage?  

I have a report that draws on the Accounts, Potentials and Stage History tables synced from ZohoCRM. The problem is that if I am showing a report of open Potentials, the join with the Stage History table means that each stage is represented by a date.  I only want to show the current stage and the date the Potential was changed to that stage.  How do I do this?