Nichole,
I don't think this is extremely obvious at all. Are you specifically looking at the field Lead Status or the lead lifecycle, such as in RCM? RCM would help you do this if you had it running, as would RCE (I think).
You could use Segment Changed to add people to a static list that gave you the count for each type of change. You could more easily do this with a Data Value Changes instead, because why use a Segmentation up?
Data Value Changes IS Lead Status from X to Y (you'll need several triggers to do this for all of the possible changes)
If X to Y, Add to List X to Y
then look at the list count.
This might not show you weekly or monthly figures unless you look at the Campaign Membership or look at the lead count at a certain point in time.
Not sure if there's a better way, but let me know if that helps.