You live in a country with a flat tax rate of 26% on all income, except for certain classes of tax-free municipal bonds. You are considering investing in two bonds that are equally risky in every respect except for their tax treatment. The present yield-to-maturity on the taxable corporate bond is 3.49%. Estimate what must be the equilibrium yield-to-maturity on the corresponding tax-free municipal bond so that will bear the same after-tax return? (The answer is a percent, round your answer to two decimal places, e.g. 4.75)