The 'population' I used here was the number of returns filed. So, joint returns count as one person in this chart, and only those who filed a return count in this chart. I think you have to be pretty close to income-less to not file a return. So this chart is also assuming that those with no income are insignificant. I don't know how good or bad that assumption is. The only ones I'd actually want to count that aren't counted are adults of working age without jobs.
It looks like the $50-75 group paid about 1% more of the total tax burden than those in the $75-100 group. There are about twice as many people in the $50-$75 group as in the $75-100 group.
The numbers in the following chart seem low, but that's probably because the total tax amount is applied after deductions and then credits are taken away from this.