|                                                       | Three Months ended March 31, 2011                                  |      |           | Years ended December 31 |
|------------------------------------------------------------|--------------------------------------------------------------------|-----------|----------------|-------------------------|
|                                                       |                                                               | 2010      |           | 2009                    |   | 2008 |   | 2007 |   | 2006 |   |
| Earnings:                                                  |                                                               |      |           |                    |   |   |   |   |   |   |   |   |   |   |
| Net (loss) income from continuing operations               | $                                                                  | (777,311) |           | $                       | (9,186,140) | $ | 4,939,365 | $ | 10,183,056 | $ | 13,876,074 | $ | 11,601,854 |   |
| Add:                                                       |                                                               |      |           |                    |   |   |   |   |   |   |   |   |   |   |
|                                                       | Income taxes expense (benefit)                                     |      | (16,073)       |                    |   | 265,986 |   | (22,293) |   | 1,927,830 |   | 761,628 |   | 965,532 |   |
|                                                       | Fixed charges, net of capitalized interest                         |      | 5,910,187      |                    |   | 28,560,292 |   | 27,350,287 |   | 29,649,915 |   | 26,257,879 |   | 21,528,608 |   |
|                                                       | Distributions and income from majority-owned unconsolidated entity |      | —   |                    |   | —   |   | 381,514 |   | 825,747 |   | 621,793 |   | 504,713 |   |
| Less:                                                      |                                                               |      |           |                    |   |   |   |   |   |   |   |   |   |   |
|                                                       | Loss (income) from unconsolidated entities                         |      | 87,625         |                    |   | 51,964 |   | (226,041) |   | (842,425) |   | (290,710) |   | (286,452) |   |
| Earnings before fixed charges and preferred dividends      | $                                                                  | 5,204,428 |           | $                       | 19,692,102 |   | 32,422,832 |   | 41,744,123 |   | 41,226,664 |   | 34,314,255 |   |
|                                                       |                                                               |      |           |                    |   |   |   |   |   |   |   |   |   |   |   |   |
| Fixed charges:                                             |                                                               |      |           |                    |   |   |   |   |   |   |   |   |   |   |
|                                                       | Interest expense                                                   | $         | 5,901,625      |                    | $ | 28,532,440 | $ | 27,151,054 | $ | 29,372,181 | $ | 25,965,141 | $ | 21,221,758 |   |
|                                                       | Capitalized interest                                               |      | 2,142,262      |                    |   | 8,807,062 |   | 8,892,218 |   | 10,061,770 |   | 12,824,398 |   | 10,680,000 |   |
|                                                       | Interest within rental expense                                     |      | 8,562          |                    |   | 27,852 |   | 20,056 |   | 16,690 |   | 16,673 |   | 16,673 |   |
|                                                       | Fixed charges of unconsolidated entities                           |      | —   |                    |   | —   |   | 179,177 |   | 261,044 |   | 276,065 |   | 290,177 |   |
| Total fixed charges                                        |                                                               | 8,052,449 |           |                    | 37,367,354 | $ | 36,242,505 | $ | 39,711,685 | $ | 39,082,277 | $ | 32,208,608 |   |
|                                                       | Preferred dividends                                                |      | 1,443,750      |                    |   | 376,979 |   | —   |   | —   |   | —   |   | —   |   |
| Total fixed charges and preferred dividends                | $                                                                  | 9,496,199 |           | $                       | 37,744,333 | $ | 36,242,505 | $ | 39,711,685 | $ | 39,082,277 | $ | 32,208,608 |   |
|                                                       |                                                               |      |           |                    |   |   |   |   |   |   |   |   |   |   |   |   |
| Ratio of earnings to fixed charges and preferred dividends |                                                               | (1)       |           |                    | (2) |   | (3) |   | 1.05 |   | 1.05 |   | 1.07 |   |

| (1)   | The ratio is less than 1.0; the amount of coverage deficiency for the three months ended March 31, 2011 was $4.3 million.  The calculation of earnings includes $9.2 million of non-cash depreciation expense. |
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| (2)   | The ratio is less than 1.0; the amount of coverage deficiency for the year ended December 31, 2010 was $18.1 million.  The calculation of earnings includes $40.7 million of non-cash depreciation expense. |
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| (3)   | The ratio is less than 1.0; the amount of coverage deficiency for the year ended December 31, 2009 was $3.8 million.  The calculation of earnings includes $32.1 million of non-cash depreciation expense. |
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