Honestly, I have no idea. I don't know why the middle class has to pay between 25-28% while the upper class has to pay 33-35% even if they make 10-20-1000x the amount of the middle class.
I think you should have to pay something like one-third of the percentile you fall under. So if you are making 3 billion dollars a year and are in the 100th percentile, you should have to pay 1 billion dollars in income taxes (fifteen percent more than currently). If you are making $125,000 a year and are in the 85th percentile, you should pay 28%, or $35,000 in taxes (about equal). If you are making $45,000 a year and are in the 50th percentile, you should pay 15%, or $6,750 in taxes (ten percent less). Etc.