14 | LETTER TO SHAREHOLDERS more than $1 billion per day in national wealth to oil exporting countries.  I am pleased to report that we have apparently finally convinced President Barack Obama and Congressional leadership to recognize that  the energy path America is on today is completely unsustainable. There  appears to be growing recognition that it is spectacularly dangerous for  America to continue importing 9 million barrels of oil per day and exporting  America’s undiminished appetite for foreign oil has created the larg- est wealth transfer in the history of the world. The political leadership  in Washington, D.C., has not seemed overly concerned about this issue  until recently. However, after President Obama’s recent speech calling  Rig lights come on at twilight in the Permian Basin of Texas, where crews drill around the clock in the liquids-rich Bone Spring play. This is the newest in a  series of energy booms that has enabled West Texas cities like Midland to prosper for almost 100 years. (3)  FORTUNE 100 Best Companies to Work For ®  listed in the magazine’s February 7, 2011 issue.  • Adjusted earnings per fully diluted share is net income (loss) per share available to Chesapeake common stockholders, assuming dilution, as adjusted to remove the effects of certain items that management  believes affect the comparability of operating results. • Operating cash flow is cash provided by operating activities before changes in assets and liabilities.  • Adjusted ebitda is net income (loss) before interest expense, income tax expense (benefit), and depreciation, depletion and amortization expense, as adjusted to remove the effects of certain items that manage - ment believes affect the comparability of operating results.  (2)  A non-GAAP financial measure, as defined below. Please refer to the Investors section of our website at www.chk.com for reconciliations of non-GAAP financial measures to comparable financial measures calculated  in accordance with generally accepted accounting principles. (1)  Reserve replacement is calculated by dividing net reserve additions from all sources by actual production for the corresponding period. We calculate drilling and net acquisition cost per mcfe by dividing total drilling  and net proved property acquisition costs incurred during the year (excludes certain costs primarily related to net unproved property acquisitions, geological and geophysical costs and deferred taxes related to  corporate acquisitions) by total proved reserve additions excluding price-related revisions. 