Item 6. SELECTED FINANCIAL DATA

The following table includes certain financial information on a consolidated historical basis. You should read this section in conjunction with “Item 7. Management’s Discussion and Analysis of Financial Condition and Results of Operations” and “Item 8. Financial Statements and Supplementary Data.”

The reconciliation of operating income to property operating income is as follows:

We consider FFO available for common shareholders a meaningful, additional measure of operating performance primarily because it excludes the assumption that the value of the real estate assets diminishes predictably over time, as implied by the historical cost convention of GAAP and the recording of depreciation. We use FFO primarily as one of several means of assessing our operating performance in comparison with other REITs. Comparison of our presentation of FFO to similarly titled measures for other REITs may not necessarily be meaningful due to possible differences in the application of the NAREIT definition used by such REITs. Additional information regarding our calculation of FFO is contained in “Item 7. Management’s Discussion and Analysis of Financial Condition and Results of Operations.”

The reconciliation of net income to FFO available for common shareholders is as follows:

(3) EBITDA is a non-GAAP measure as calculated in the table below. Adjusted EBITDA is a non-GAAP measure that means net income or loss plus net interest expense, income taxes, depreciation and amortization, gain or loss on sale of real estate and impairments of real estate if any. Adjusted EBITDA is presented because it approximates a key performance measure in our debt covenants, but it should not be considered an alternative measure of operating results or cash flow from operations as determined in accordance with GAAP. Adjusted EBITDA as presented may not be comparable to other similarly titled measures used by other REITs.

The reconciliation of net income to EBITDA and adjusted EBITDA for the periods presented is as follows:

(4) Fixed charges consist of interest on borrowed funds (including capitalized interest), amortization of debt discount/ premiums and debt costs, costs related to the early extinguishment of debt, and the portion of rent expense representing an interest factor. Excluding the $12.3 million, $19.1 million, $10.5 million, and $13.3 million early extinguishment of debt charge from fixed charges in 2017, 2015, 2014, and 2013, respectively, the ratio of EBITDA and adjusted EBITDA to combined fixed charges and preferred share dividends is 4.8x and 4.2x, respectively, for 2017, 4.5x and 4.3x, respectively, for 2015, 3.9x and 3.8x, respectively, for 2014, and 3.7x and 3.4x, respectively for 2013.