EXHIBIT 12 Computation of Ratio of Earnings to Combined Fixed Charges and Preferred Stock Dividends (Dollars in thousands) Three Months ended June 30, Six Months ended June 30, ------------------------------ ------------------------------ 1998 1997 1998 1997 ------------- -------------- -------------- -------------- Net income $35,005 $14,677 $52,189 $31,790 Add: Portion of rents representative of the interest factor 133 105 246 194 Interest on indebtedness 25,736 19,769 48,561 38,919 ------------- -------------- -------------- -------------- Earnings $60,874 $34,551 $100,996 $70,903 ============= ============== ============== ============== Fixed charges and preferred stock dividend: Interest on indebtedness $25,736 $19,769 $48,561 $38,919 Capitalized interest 777 721 1,312 1,230 Portion of rents representative of the interest factor 133 105 246 194 ------------- -------------- -------------- -------------- Fixed charges 26,646 20,595 50,119 40,343 ------------- -------------- -------------- -------------- Add: Preferred stock dividend 5,653 3,611 11,303 6,039 ------------- -------------- -------------- -------------- Combined fixed charges and preferred stock dividend $32,299 $24,206 $61,422 $46,382 ============= ============== ============== ============== Ratio of earnings to fixed charges 22.8x 1.68x 2.02x 1.76x Ratio of earnings to combined fixed charges and preferred stock dividend 1.88 1.43 1.64 1.53