Is there A Level Difference Experience Chart/ Reference?

I am wondering how much beneath the monster max level can you go for full experience.

ex level 70 killing level 80 monsters giving 80% xp

ex level 70 killing 74 monsters giving 100% xp

Thank you kindly ahead of time

I am interested in this, too

(((monsterLevel12.75-(averagePartyLevelaveragePartyLevel/50))+((monsterLevel-averagePartyLevel)*(averagePartyLevel/1.12)))0.098)(1+(monsterExperience/100))+3

just fill in the blanks, I think that is the original equation.