In order to raise revenue, the federal government planned a tax amnesty program that allows tax delinquents to pay all owed tax without added financial penalty. However, economists projected that the federal government would collect a far lower percentage of total tax owed by delinquents than did state governments implementing similar programs.

Which of the following, if true, would most contribute to an explanation of the economists' projections?

【选项】The state tax rate varies considerably from state to state, but the federal tax is levied according to laws which apply to citizens of all the states.