(2021 Summer Final) Suppose there are 7 persons in the economy with the following willingness to pay for a good. At the price ceiling of $4.4, only 3 units are supplied. Consider the allocation ofgoods based on bribery. Suppose the amount of bribe can be observed by everyone, the equilibrium amount of bribe in this market has to be strictly higher than $[Answer] per unit. (In decimal numbers, with two decimal places, please.)