Its basics of maths. My english is too bad to explain it correctly, but those displayed 1% are not the same 1%. Once the value becomes it, its not the bottom, when you promote (or do upselling like this asso team) it falls "under 1%" but "1" still displayed. (So this percentage system is sort of fake, not the one we all know)
Therefore you have to calculate the absolute values for the average power, not the relative. After that you could translate it back to "%"