In 1970, Wal-Mart offered 300,000 shares of its common stock to the public at a price of $16.50 per share. Since that time, Wal-Mart has had 11 two-for-one stock splits. On a purchase of 100 shares at $16.50 per share on the company's first offering, the number of shares has grown to 204,800 shares worth $10,887,600 in January 2010. What is the return on investment for investors who purchased the stock in 1970 (over a 40-year ownership period)? Assume that no dividends were received during that period.