Suppose you buy 100 shares of NORG Corporation at the beginning of year 1 for $80. NORG pays no dividends. The share price at the end of year 1 is $100, $120 at the end of year 2, and $150 at the end of year 3. The share price declines to $100 at the end of year 4, and you sell your 100 shares. Calculate the geometric average return (in %) for the four years.