How to report on how long a candidate has been in a particular phase and state

Summary:

I would like to report on the length of time that candidates remains in each phase and related state.

Content (required):

A report that shows how long candidates are in each phase and state is important as it helps recruiting teams analyse: a candidates journey, where recruiting teams may need to redirect resources, identify blockers and process issues relating to time to hire. However, I'm struggling to get at this data. In OTBI the event date seemed like the right place to start however, this is reporting on every event in a state e.g. if a notification and a move is triggered then both these events are reported on. What is actually required is an entry and exit time stamp to