**EXHIBIT 12**

 

**COMPUTATION OF RATIOS**

**(UNAUDITED)**

 

Our consolidated ratios of earnings to fixed charges and earnings to combined fixed charges and preference distributions for each of the fiscal years ended December 31, 2007, 2006, 2005, 2004 and 2003 are as follows:

 

|                                                                                               |   | **Year Ended December 31,** |          |
|----------------------------------------------------------------------------------------------------|--------|-----------------------------|---------------|
| ($ in thousands)                                                                                   |   | **2007**                    |          | **2006** |   | **2005** |   | **2004** |   | **2003** |   |
| Net income from continuing operations                                                              |   | $                           | 576,972       |   | $ | 603,105 |   | $ | 632,458 |   | $ | 661,564 |   | $ | 451,397 |   |
| Fixed charges and preference dividends                                                             |   |                        | 965,420       |   |   | 810,122 |   |   | 565,320 |   |   | 421,568 |   |   | 423,567 |   |
| Minority interest in the Operating Partnership not included in fixed charges                       |   |                        | (18,559       | ) |   | (20,173 | ) |   | 3,808 |   |   | 109 |   |   | 1,089 |   |
| Capitalized interest                                                                               |   |                        | (53,648       | ) |   | (26,195 | ) |   | (15,582 | ) |   | (8,718 | ) |   | (5,407 | ) |
| Equity in income of partially-owned entities in excess of distributions                            |   |                        | (13,352       | ) |   | — |   |   | — |   |   | (26,624 | ) |   | — |   |
|                                                                                               |   |                        |          |   |   |   |   |   |   |   |   |   |   |   |   |   |
| **Earnings - Numerator**                                                                           |   | **$**                       | **1,456,833** |   | **$** | **1,366,859** |   | **$** | **1,186,004** |   | **$** | **1,047,899** |   | **$** | **870,655** |   |
|                                                                                               |   |                        |          |   |   |   |   |   |   |   |   |   |   |   |   |   |
| Interest and debt expense, including the Company’s pro-rata share of partially-owned entities |   | $                           | 823,030       |   | $ | 692,496 |   | $ | 415,826 |   | $ | 313,289 |   | $ | 296,059 |   |
| Capitalized interest                                                                               |   |                        | 53,648        |   |   | 26,195 |   |   | 15,582 |   |   | 8,718 |   |   | 5,407 |   |
| 1/3 of rental expense – interest factor                                                       |   |                        | 11,848        |   |   | 9,490 |   |   | 7,382 |   |   | 5,491 |   |   | 5,491 |   |
| **Fixed charges - Denominator**                                                                    |   |                        | **888,526**   |   |   | **728,181** |   |   | **438,790** |   |   | **327,498** |   |   | **306,957** |   |
| Preferred unit distributions, a component of minority interest                                     |   |                        | 76,894        |   |   | 81,941 |   |   | 126,530 |   |   | 94,070 |   |   | 116,619 |   |
| **Combined fixed charges and preference dividends - Denominator**                                  |   | **$**                       | **965,420**   |   | **$** | **810,122** |   | **$** | **565,320** |   | **$** | **421,568** |   | **$** | **423,576** |   |
|                                                                                               |   |                        |          |   |   |   |   |   |   |   |   |   |   |   |   |   |
| **Ratio of earnings to fixed charges**                                                             |   |                        | **1.64**      |   |   | **1.88** |   |   | **2.70** |   |   | **3.20** |   |   | **2.84** |   |
| **Ratio of earnings to combined fixed charges and preference distributions**                       |   |                        | **1.51**      |   |   | **1.69** |   |   | **2.10** |   |   | **2.49** |   |   | **2.06** |   |

 

Earnings equals (i) income from continuing operations before income taxes plus, (ii) minority interest not included in fixed charges and (iii) fixed charges, minus (iv) equity in income of partially-owned entities in excess of distributions and (v) capitalized interest. Fixed charges equals (i) interest debt expense, plus (ii) the Company’s pro-rata share of interest expense of partially-owned entities, (iii) capitalized interest and (iv) the portion of operating lease rental expense that is representative of the interest factor, which is one-third of operating lease rentals. Combined fixed charges and preference distributions equals fixed charges plus preferred unit distributions.