The rate should be increased to eliminate all forms of government subsidy for postal service, including the exemptions from certain state and local taxes and licensing requirements for the USPS' competitive products operations. These subsidies are worth between $39 million and $117 million a year, according to Federal Trade Commission.
That's not simply a matter of dividing the value of the subsidies by the number of pieces of mail and adding that to the postage rate, because increasing the postage rate will necessarily decrease the number of pieces of mail. So the rate increase would need to be grossed-up to address that.