Exhibit 12

COMPUTATION OF

RATIO OF EARNINGS TO FIXED CHARGES

(in thousands)

	Year Ended December 31,															Nine Months Ended September 30,
	2003			2004			2005			2006			2007			2007			2008
Total Interest Cost
Interest Expense	$	18,523		$	17,698		$	12,558		$	17,675		$	15,697		$	12,898		$	4,105
Capitalized Interest		2,734			3,004			3,869			2,553			8,336			5,773			15,702
Total Interest Cost (fixed charges)		21,257			20,702			16,427			20,228			24,033			18,671			19,807
Pre-tax Income		18,048			(3,803	)		58,981			118,874			148,601			108,186			127,740
Interest Expense		18,523			17,698			12,558			17,675			15,697			12,898			4,105
Earnings		36,571			13,895			71,539			136,549			164,298			121,084			131,845
Ratio of earnings to fixed charges(1)(2)(3)		1.7	x		—			4.4	x		6.8	x		6.8	x		6.5	x		6.7	x

(1) We have authority to issue up to 5,000 shares of preferred stock, par value $.01 per share; however, there are currently no such shares outstanding and we do not have a preferred stock dividend obligation. Therefore, the ratio of earnings to fixed charges and preferred stock dividends is equal to the ratio of earnings to fixed charges and is not disclosed separately.

(2) For the year ended December 31, 2004, earnings were inadequate to cover fixed charges by $6.8 million. If we adjust earnings to exclude the impact of loss on the early extinguishment of debt incurred in the 2004 and 2005 periods reflected above, the ratio of earnings to fixed charges, as so adjusted, would be 1.8x and 4.5x for the years ended December 31, 2004 and 2005, respectively.

(3) Effective January 1, 2009, we will be required to adopt FASB Staff Position (FSP) No. APB 14-1, “Accounting for Convertible Debt Instruments That May Be Settled in Cash upon Conversion (Including Partial Cash Settlements).” FSP No. APB 14-1 requires that the liability and equity components of a convertible debt instrument within the scope of the FSP be accounted for separately so that the entity’s accounting will reflect additional non-cash interest expense to match the nonconvertible debt borrowing rate when interest cost is recognized in subsequent periods. FSP No. APB 14-1 requires retrospective application to all periods. The Company is still evaluating the effects of this new standard, but expects interest expense to increase and, therefore, the ratio of earnings to fixed charges to change, for periods after the November 13, 2006 issuance of our Convertible Senior Notes.