Exhibit 12.1

Ratio of Earnings to Fixed Charges

The following table sets forth our ratios of consolidated earnings to fixed charges for the periods presented:

	Year Ended December 31,
	2011			2010			2009			2008			2007
	(in thousands except ratios) (unaudited)
Income before income taxes	$	264,334		$	129,793		$	(262,030	)	$	(828,482	)	$	215,759
Add: Fixed charges		62,458			43,304			46,974			54,213			62,438
Add: Amortization of capitalized interest		860			1,353			2,667			1,273			1,265
Less: Capitalized Interest		(9,877	)		(5,395	)		(6,662	)		(19,292	)		(25,100	)
Earnings before fixed charges	$	317,775		$	169,055		$	(219,051	)	$	(792,288	)	$	254,362
Fixed Charges:
Interest expense, net of capitalized interest	$	52,393		$	37,706		$	40,087		$	34,709		$	37,088
Capitalized interest		9,877			5,395			6,662			19,292			25,100
Portion of rental expense representative of an interest factor		188			203			225			212			250
Total fixed charges	$	62,458		$	43,304		$	46,974		$	54,213		$	62,438
Ratio of earnings to fixed charges		5.1			3.9			—	(1)		—	(2)		4.1

(1) Earnings were inadequate to cover fixed charges for the year ended December 31, 2009 by $266.0 million. Earnings for the year ended December 31, 2009 included an impairment write down of $218.9 million.

(2) Earnings were inadequate to cover fixed charges for the year ended December 31, 2008 by $846.5 million. Earnings for the year ended December 31, 2008 included an impairment write down of $1,182.8 million.