1930 to 1935, 37%.
Work Step by Step
The 5-year period during which the top marginal tax rate increased by highest amount will be the answer. As per the graph, the tax rate increased by highest amount between 1930 and 1935. So this is the answer. Also, the tax rate at 1935 can be estimated to be 62%, And, the tax rate at 1930 can be estimated to be 25%, So, the increase in tax rate is 62%-25%=37%.