The “drown Uncle Sam in a bathtub” crowd likes to point to the point to the rate cuts enacted under the Democrats in the early sixties. They brought the top marginal individual rate down to 77 percent. http://ntu.org/tax-basics/history-of-federal-individual-1.html. Down from 91 percent.
That 77 percent rate is still too high for me. There is some scholarship about finding the revenue-maximizing point on the Laffer curve (my allies think maybe low sixties). But this issue of the right top rate is like theology: each of us is unlikely to make personal converts among those who disagree with us.
The Center for New Revenue 