Party Player Points Bonus

[Prodigy]

mine hit earlier yesterday morning (Wednesday 11/02). I had to clear 9800 bonus pts for $2015. On my younger brother's account, he had to clear 12000pts for a paltry $500. How do they come up w/ these account specific figures?
I did run bad on party on August and part of September. I generally play 10-20 6max and 20-40 stud mixed in w/ Stud8, totaling 4 tables. Occasionally, I will play 30-60 Ring Game. My friend who plays 1 table of 100-200 on a regular basis only got $900 after clearing the bonus. So how do they come up w/ these figures again?