Exhibit 12.1

Statement of Computation of Ratios of Earnings to Fixed Charges

	Three Months Ended March 31,			Year Ended December 31,
	2012			2011			2010			2009			2008			2007
Earnings:
Income before income taxes	$	223.1		$	906.4		$	877.0		$	865.0		$	159.3		$	468.1
Interest expense		105.8			448.3			513.7			603.7			134.4			97.8
Interest component of rent		3.7			16.6			17.2			20.0			5.1			3.8
Capitalized Interest		(1.5	)		(8.1	)		(6.3	)		(7.8	)		(2.6	)		(3.1	)
Total earnings for ratio		331.1			1,363.2			1,401.6			1,480.9			296.2			566.6
Fixed Charges:
Interest expense		105.8			448.3			513.7			603.7			134.4			97.8
Interest component of rent		3.7			16.6			17.2			20.0			5.1			3.8
Total interest for ratio	$	109.5		$	464.9		$	530.9		$	623.7		$	139.5		$	101.6
Earnings to fixed charges		3.0			2.9			2.6			2.4			2.1			5.6