EXHIBIT 12

COMPUTATION OF RATIO OF EARNINGS TO FIXED CHARGES

	Twelve Months Ended				Three Months Ended
	Dec. 31		Dec. 31		Dec. 31		Dec. 31
	2005		2004		2005		2004
	(Thousands of dollars, except ratio amounts)
Income before income taxes	$	390,546	$	199,779	$	149,285	$	84,821
Share of undistributed losses from 50%-or-less-owned affiliates, excluding affiliates with guaranteed debt		4,762		5,462		1,089		1,599
Amortization of capitalized interest		1,288		1,352		322		341
Interest expense		51,585		50,834		12,209		14,893
Interest portion of rental expense		4,428		1,866		2,261		963
Earnings	$	452,609	$	259,293	$	165,166	$	102,617
Interest	$	52,205	$	51,375	$	12,366	$	15,076
Interest portion of rental expense		4,428		1,866		2,261		963
Interest expense relating to guaranteed debt of 50%-or-less-owned affiliates		—		106		—		—
Fixed Charges	$	56,633	$	53,347	$	14,627	$	16,039
Ratio of Earnings to Fixed Charges		7.99		4.86		11.29		6.40