A firm is considering purchasing new drilling equipment for its oil rig. -The cost of the equipment is $117,000. The firm will pay for the drilling equipment in year 0. -Project life: 4 years -Salvage value in year 0 (constant) dollars: $13,000 -Depreciation method: five-years MACRS -Tax rate = 21% (remains constant over time) -Annual revenue = $147,000 (year-0 constant dollars) -Annual expenses = $95,000 (year-0 constant dollars) If the general inflation rate is 3.9% during the project period (which will affect all revenues, expenses, and the salvage value), determine the INFLATION-FREE rate of return of the drilling equipment. Enter your answer as a percentage between 0 and 100 rounded to the nearest tenth of a percent.