Suppose that you buy a bond with face value $1,000 that was originally issued 18 months ago. The maturity date is 4 years from the time it was issued, and the interest rate is 4% simple interest per year. If you pay $820 for the bond and keep it until the maturity date, what is your profit? What percent of your investment is the profit made? (Round to one decimal place; Give your answer as a percentage; and Do not include the percent symbol with your answer)