you should use other axes, X axis (killed-summoned) aka base monsters, Y axis XP multiplier, and curves (monsters summoned). I think it will be a not more representable this way. Also logarythmic steps could be required for curves, 100-400-1600-6400-etc.
Since this thread is almost two years old and the last post is over a year, I'm locking this. And please, don't bring back threads that are so old. Thanks