Cap child support

Put a cap on the amount of money ex-spouses are entitled to as a result of divorce involving children. Former parents are punished by bettering themselves as they carry-on with their lives after the marriage is over. There should be some sort of cap on the amount of child support a former spouse receives after the marriage is disolved.
If a former parent gets a raise / promotion or a better job, that parent is once again dragged into court by a vengeful or greedy ex-spouse in order to cash-in on that benefit. A former spouse should have no right to any of that added income since the gain came after the marriage was over with. The ambitious parent is again targeted by the court system to give up 20% of his newly found income.
There should be some sort of cap on the 20% child support rule as well as a recuction in the percentage. Former spouses do not deserve 20%. Why not 10%?
In today's society we are bombarded by taxes. We pay approximately 8% in sales taxes. As employees, we pay anywhere from 20% to 30% in taxes, depending on if you are your own boss or not. As a property owner, one is taxed about 10%. Some states also have a state tax on top of that. The church wants its 10%. Then on top of that, we are supposed to pay 20% in child support? If you calculate those percentages, in a worst-case scenario, one would have to live off of only about 21% of the income! Now, that is no way to live. What kind of message is that sending when, as soon as one gets a raise, it is widdled away by a former spouse?
A former spouse can keep tapping a the other's income as long as the child is of age to qualify for child support. It gets out of hand when successful people end up having to pay anywhere from $5,000 to $8,000 a month or more!
Now, why would any former spouse need so much money? The Government itself puts a cap on the amount of money it provides to single parents, and even then, it does not give the money in full. Some of the money is issued out in the form of food stamps or something of the like.
We need to put a cap on child support per year. the cap needs to be a percentage of the minimum amount needed to support the child for one year/ per year in that area or state. Better yet, a percentage of the national poverty level per year. That would be a fair and impartial process for all.
If the spouse says they still can't provide for their child, then the child should go to the parent who can.
Let common sense prevail!