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 for Real Estate ("EBITDAre") is a non-GAAP measure that NAREIT defines as: net income computed in accordance with GAAP plus net interest expense, income tax expense, depreciation and amortization, gain or loss on sale of real estate, impairments of real estate, and adjustments to reflect the entity's share of EBITDAre of unconsolidated affiliates. We calculate EBITDAre consistent with the NAREIT definition. As EBITDA is a widely known and understood measure of performance, management believes EBITDAre represents an additional non-GAAP performance measure, independent of a company's capital structure that will provide investors with a uniform basis to measure the enterprise value of a company. EBITDAre also 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.

The reconciliation of net income to EBITDAre 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 early extinguishment of debt charge from fixed charges in 2017, 2015, and 2014, respectively, the ratio of EBITDAre to combined fixed charges and preferred share dividends is 4.2x, 4.3x, and 3.8x, for 2017, 2015, and 2014, respectively.