A small start-up company invested in a new plant with an initial cost of $10 million. Operating costs for the plant were $3 million per year for 7 years. There was a special one-time charge of $1 million in year 2 to correct unexpected equipment problems. Revenues were $3 million in year 1, and increased by $1 million per thereafter through year 7. Determine the company's rate of return on this investment.