Exhibit 12.1

Computation of Ratio of Earnings to Fixed Charges

(unaudited)

(in thousands of dollars, except ratios)

	Six Months Ended June 30,
			Year Ended December 31,
	2013		2012		2011		2010		2009		2008
Earnings before fixed charges		99,721		256,062		186,319		108,926		69,413		65,140
Fixed Charges:
Interest expenses including amortization of deferred financing costs		21,187		21,494		28,425		36,897		35,722		22,010
Assumed interest component of rental expenses (1)		1,587		3,008		2,965		2,753		1,999		1,167
Total fixed charges		22,774		24,502		31,390		39,650		37,721		23,177
Earnings (2)		122,495		280,564		217,709		148,576		107,134		88,317
Ratio of earnings to fixed charges (3)		5.38		11.45		6.94		3.75		2.84		3.81
Deficiency of earnings to fixed charges		—		—		—		—		—		—

(1) Estimated as one-third of operating lease expense.

(2) Earnings represent pre-tax income (loss) from continuing operations before adjustments for non-controlling interests in consolidated subsidiaries or income (loss) from equity investees plus distributed income of equity investees, and plus fixed charges.

(3) During the periods covered by this table, we did not have any shares of preferred stock outstanding.