Exhibit 12.1

Ratio of Earnings to Combined Fixed Charges and Preferred Stock Dividends and Ratio of Earnings to Fixed Charges

(Unaudited)

	For the Three Months Ended March 31,				For the Years Ended December 31,
	2018		2017		2017		2016		2015		2014			2013
					(dollars in thousands)
Ratio of earnings to fixed charges:
Fixed charges (interest expense)(1)	$	415,581	$	302,581	$	1,379,462	$	1,164,433	$	1,096,091	$	1,338,019		$	1,533,008
Net income (loss) available (attributable) to common shareholders before income taxes (2)		1,294,502		417,912		1,466,363		1,348,931		391,825		(908,922	)		3,665,943
Earnings as adjusted	$	1,710,083	$	720,493	$	2,845,825	$	2,513,364	$	1,487,916	$	429,097		$	5,198,951
Ratio of earnings to fixed charges		4.11		2.38		2.06		2.16		1.36		0.32			3.39
Ratio of earnings to combined fixed charges and preferred stock dividends:
Fixed charges (interest expense) (1)	$	415,581	$	302,581	$	1,379,462	$	1,164,433	$	1,096,091	$	1,338,019		$	1,533,008
Preferred stock dividend		33,766		23,473		109,635		82,260		71,968		71,968			71,968
Combined fixed charges and preferred stock dividends		449,347		326,054		1,489,097		1,246,693		1,168,059		1,409,987			1,604,976
Net income (loss) available (attributable) to common shareholders before income taxes (2)	$	1,294,502	$	417,912		1,466,363		1,348,931		391,825		(908,922	)		3,665,943
Earnings as adjusted	$	1,743,849	$	743,966	$	2,955,460	$	2,595,624	$	1,559,884	$	501,065		$	5,270,919
Ratio of earnings to combined fixed charges and preferred stock dividends		3.88		2.28		1.98		2.08		1.34		0.36			3.28

  (1)  Fixed charges include realized gains (losses) on interest rate swaps.

  (2)  Includes unrealized gains (losses) on investments and/or derivatives.