In September 2022, a U.S. investor chooses to invest $500,000 in German equity securities at an average price of 60/share and at the current spot exchange rate of $1.25/euro. At the end of the year the investor sells his stock that has an average price per share of 70 and at the spot exchange rate of $1.10/euro. What is the investor's average rate of return after converting the stock back into dollars?