200 Greatest

I am watching on youtube the 200 Greatest Pop Culture Icons. Oprah was #1. I did not get some of the ranking though. You had Aretha Franklin at #103, Diana Ross at #165, and JFK at #32 but Brittany Spears at #20 and JLo at #15. This does not seem very accurate to me. Aretha, Diana, JFK made a greater impact than JLO or Brittany Spears. What did VH1 base this off of?