Exhibit 12a
<TABLE>
                                      STATEMENT SETTING FORTH COMPUTATIONS OF RATIOS OF
                                                  EARNINGS TO FIXED CHARGES
                                                    (Dollars in Thousands)
<CAPTION>
                                                  12 Months
                                                     Ending                    Year Ended December 31,
                                             March 31, 2000        1999         1998         1997        1996         1995
------------------------------------- ---------------------- ----------- ------------ ------------ ----------- ------------
<S>                                   <C>                    <C>         <C>          <C>          <C>         <C>
EARNINGS AVAILABLE FOR
 FIXED CHARGES
  Pre-tax income:
    Income from continuing

      operations per statement
      of income                                    $194,004    $185,567     $169,612     $125,698    $167,351     $128,382
    Federal income taxes                            111,066     109,164      105,814       44,916     106,876       91,519
    Federal income taxes charged
      to other income - net                           4,377       2,909        3,986       14,807        (784)     (11,967)
    Capitalized interest                             (3,442)     (3,692)      (1,782)        (360)       (600)        (660)
    Undistributed (earnings) or
      losses of less-than-
      fifty-percent-owned
      entities                                           --          --           --        (608)         460        8,325
------------------------------------- ---------------------- ----------- ------------ ------------ ----------- ------------
Total                                              $306,005    $293,948     $277,630     $184,453    $273,303     $215,599
------------------------------------- ---------------------- ----------- ------------ ------------ ----------- ------------

  Fixed charges:
    Interest expense                               $167,882    $160,966     $146,248     $123,543    $122,635     $131,346
    Other interest                                    3,442       3,692        1,782          360         600          660
    Portion of rentals
      representative of the
      interest factor                                 4,572       4,575        2,878        3,143       4,187        5,150
------------------------------------- ---------------------- ----------- ------------ ------------ ----------- ------------
Total                                              $175,896    $169,233     $150,908     $127,046    $127,422     $137,156
------------------------------------- ---------------------- ----------- ------------ ------------ ----------- ------------

  Earnings available for

    combined fixed charges                         $481,901    $463,181     $428,538     $311,499    $400,725     $352,755
RATIO OF EARNINGS TO
  FIXED CHARGES                                       2.74x       2.74x        2.84x        2.45x       3.14x        2.57x
</TABLE>

                                       1
<PAGE>


Exhibit 12b
<TABLE>
                                      STATEMENT SETTING FORTH COMPUTATIONS OF RATIOS OF
                              EARNINGS TO COMBINED FIXED CHARGES AND PREFERRED STOCK DIVIDENDS
                                                    (Dollars in Thousands)
<CAPTION>
                                                 12 Months
                                                    Ending                       Year Ended December 31,
                                             March 31, 2000         1999         1998         1997         1996         1995
------------------------------------- ---------------------- ------------ ------------ ------------ ------------ ------------
<S>                                   <C>                    <C>          <C>          <C>          <C>          <C>
EARNINGS AVAILABLE FOR COMBINED
 FIXED CHARGES AND PREFERRED
 DIVIDEND REQUIREMENTS

  Pretax income:
    Income from continuing

      operations per statement
      of income                                    $194,004     $185,567     $169,612     $125,698     $167,351     $128,382
    Federal income taxes                            111,066      109,164      105,814       44,916      106,876       91,519
    Federal income taxes charged
      to other income - net                           4,377        2,909        3,986       14,807         (784)     (11,967)
------------------------------------- ---------------------- ------------ ------------ ------------ ------------ ------------
Subtotal                                            309,447      297,640      279,412      185,421      273,443      207,934
  Capitalized interest                               (3,442)      (3,692)      (1,782)        (360)        (600)        (660)
  Undistributed (earnings) or
    losses of less-than-fifty-
    percent-owned entities                               --           --          --          (608)         460        8,325
------------------------------------- ---------------------- ------------ ------------ ------------ ------------ ------------
Total                                              $306,005     $293,948     $277,630     $184,453     $273,303     $215,599
------------------------------------- ---------------------- ------------ ------------ ------------ ------------ ------------

  Fixed charges:
    Interest expense                               $167,882     $160,966     $146,248     $123,543     $122,635     $131,346
    Other interest                                    3,442        3,692        1,782          360          600          660
    Portion of rentals
      representative of the
      interest factor                                 4,572        4,575        2,878        3,143        4,187        5,150
------------------------------------- ---------------------- ------------ ------------ ------------ ------------ ------------
Total                                              $175,896     $169,233     $150,908     $127,046     $127,422     $137,156
------------------------------------- ---------------------- ------------ ------------ ------------ ------------ ------------

Earnings available for
  combined fixed charges
  and preferred dividend
  requirements                                     $481,901     $463,181     $428,538     $311,499     $400,725     $352,755

DIVIDEND REQUIREMENT:
  Fixed charges above                              $175,896     $169,233     $150,908     $127,046     $127,422     $137,156
  Preferred dividend
    requirements below                               16,736       17,747       21,421       26,266       36,242       36,693
------------------------------------- ---------------------- ------------ ------------ ------------ ------------ ------------
Total                                              $192,632     $186,980     $172,329     $153,312     $163,664     $173,849
------------------------------------- ---------------------- ------------ ------------ ------------ ------------ ------------
</TABLE>


                                       2
<PAGE>

<TABLE>
<CAPTION>
                                                    12 Months
                                                       Ending                     Year Ended December 31,
                                               March 31, 2000        1999         1998         1997        1996         1995
--------------------------------------- ---------------------- ----------- ------------ ------------ ----------- ------------
<S>                                     <C>                    <C>         <C>          <C>          <C>         <C>
RATIO OF EARNINGS TO COMBINED
  FIXED CHARGES AND PREFERRED
  DIVIDEND REQUIREMENTS                                  2.50        2.48         2.49         2.03        2.45         2.03

COMPUTATION OF PREFERRED
  DIVIDEND REQUIREMENTS:
  (a) Pre-tax income                                 $309,447    $297,640     $279,412    $185, 421    $273,443     $207,934
  (b) Income from continuing
        operations                                    194,004    $185,567     $169,612     $125,698    $167,351     $128,382
  (c) Ratio of (a) to (b)                              1.5951      1.6039       1.6474       1.4751      1.6339       1.6197
  (d) Preferred dividends                            $ 10,492    $ 11,065     $ 13,003     $ 17,806    $ 22,181     $ 22,654
  Preferred dividend
    requirements

      [(d) multiplied by (c)]                        $ 16,736    $ 17,747     $ 21,421     $ 26,266    $ 36,242     $ 36,693


                                       3
</TABLE>