An investor was afraid that he would become like King Lear in his retirement and beg hospitality from his children, so he purchased grain "tithes," or shares in farm output, for 580 pounds. The tithes paid him 67 pounds per year for 33 years. Required: What interest rate did the he receive on this investment? (Round your answer as directed, but do not use rounded numbers in intermediate calculations. Enter your answer as a percent rounded to 2 decimal places (e.g., 32.16).) Interest rate %