There are three types of tax rate structures: (1) progressive rate, (2) proportional rate, and (3) regressive rate. The US Federal income tax system currently applies the progressive tax rate structure. A common controversy is whether the progressive tax rate is the best application for the US. Many believe that the proportional tax rate would be a better system for the US Federal income tax rate system. Identify the differences between the three tax rate structures. In your opinion, what structure would be the best structure for the US? Be sure to support your answer with the advantages of the method you select and the disadvantages of the other tax rate structures.