Exhibit 12

Statement re: Calculation of Ratios of Earnings to

Combined Fixed Charges and Preferred Unit Distributions

(Dollars in thousands)

	Nine Months Ended September 30, 2006		Year Ended December 31, 2005		Year Ended December 31, 2004		Year Ended December 31, 2003		Year Ended December 31, 2002		Year Ended December 31, 2001
Net income from continuing operations less preferred distributions	$	56,988	$	102,815	$	118,355	$	123,437	$	130,070	$	200,784
Preferred distributions	41,193		46,479		33,777		39,225		52,613		60,850
Interest expense	133,288		116,716		107,158		98,325		85,697		81,767
Earnings before fixed charges	$	231,469	$	266,010	$	259,290	$	260,987	$	268,380	$	343,401
Interest expense	$	133,288	$	116,716	$	107,158	$	98,325	$	85,697	$	81,767
Interest costs capitalized	24,567		9,510		5,961		6,734		13,529		25,859
Total fixed charges	$	157,855	$	126,226	$	113,119	$	105,059	$	99,226	$	107,626
Preferred distributions	$	41,193	$	46,479	$	33,777	$	39,225	$	52,613	$	60,850
Total fixed charges and preferred distributions	$	199,048	$	172,705	$	146,896	$	144,284	$	151,839	$	168,476
Ratio of Earnings to Fixed Charges	1.47		2.11		2.29		2.48		2.70		3.19
Ratio of Earnings to Combined Fixed Charges and Preferred Distributions	1.16		1.54		1.77		1.81		1.77		2.04