Here, let me take a wild stab at it:

Taking aggregation for it's original Latin meaning, "Aggregation comes from the Latin ad, meaning 'to', and gregare, meaning 'herd'. So the word was first used to literally mean to herd or to flock."

P = time

Y axis = the concentration/population/"hang out locations" of sheep which steadily increases (or decreases) over time because, you know, animals like to mate, congregate, and die for extremely variable reasons.

So, clearly, this was a graph that a shepherd made in his spare time to roughly record the activity/population of his sheep. Kind of careless of him not to include the Y axis (or any clear, definable labels for that matter) though...

:lol: :lol: :lol: 

Edit: I should probably add that I've never been amazing with graphs...hehehe