EXHIBIT 12

STATEMENT REGARDING COMPUTATION OF RATIO OF EARNINGS
TO FIXED CHARGES AND RATIO OF EARNINGS TO COMBINED FIXED
CHARGES AND PREFERRED STOCK DIVIDENDS
(UNAUDITED)

																Three Months
																Ended
	Year Ended December 31															March 31
	2001			2002			2003			2004			2005			2005			2006
	(dollars in thousands)
Earnings:
Income from continuing operations before extraordinary items (1)	$	50,200		$	57,524		$	70,736		$	81,118		$	78,127		$	22,741		$	23,155
Fixed charges		34,644			44,644			59,833			76,824			85,999			20,773			25,151
Capitalized interest		(841	)		(170	)		(1,535	)		(875	)		(665	)		(265	)		(202	)
Equity (earnings) losses in less than 50% owned subsidiary		(332	)		(15	)		(270	)
Earnings	$	83,671		$	101,983		$	128,764		$	157,067		$	163,461		$	43,249		$	48,104
Fixed charges:
Interest expense (2)	$	32,028		$	42,101		$	55,377		$	72,556		$	82,624		$	19,645		$	24,238
Capitalized interest		841			170			1,535			875			665			265			202
Amortization of loan expenses		1,775			2,373			2,921			3,393			2,710			863			711
Fixed charges	$	34,644		$	44,644		$	59,833		$	76,824		$	85,999		$	20,773		$	25,151
Consolidated ratio of earnings to fixed charges		2.42			2.28			2.15			2.04			1.90			2.08			1.91
Earnings:
Income from continuing operations before extraordinary items (1)	$	50,200		$	57,524		$	70,736		$	81,118		$	78,127		$	22,741		$	23,155
Fixed charges		34,644			44,644			59,833			76,824			85,999			20,773			25,151
Capitalized interest		(841	)		(170	)		(1,535	)		(875	)		(665	)		(265	)		(202	)
Equity (earnings) losses in less than 50% owned subsidiary		(332	)		(15	)		(270	)
Earnings	$	83,671		$	101,983		$	128,764		$	157,067		$	163,461		$	43,249		$	48,104
Fixed charges:
Interest expense (2)	$	32,028		$	42,101		$	55,377		$	72,556		$	82,624		$	19,645		$	24,238
Capitalized interest		841			170			1,535			875			665			265			202
Amortization of loan expenses		1,775			2,373			2,921			3,393			2,710			863			711
Fixed charges		34,644			44,644			59,833			76,824			85,999			20,773			25,151
Preferred stock dividends		13,505			12,468			9,218			12,737			21,594			5,436			5,333
Combined fixed charges and preferred stock dividends	$	48,149		$	57,112		$	69,051		$	89,561		$	107,593		$	26,209		$	30,484
Consolidated ratio of earnings to combined fixed charges and preferred stock dividends		1.74			1.79			1.86			1.75			1.52			1.65			1.58

(1)	In accordance with FASB Statement No. 144, we have reclassified the income and expenses attributable to the properties sold subsequent to January 1, 2002 and attributable to properties held for sale at March 31, 2006 to discontinued operations.
(2)	For purposes of this statement, interest expense consists of interest on all indebtedness including amounts allocated to discontinued operations, in accordance with FASB Statement No. 144.