Vulcan Materials Company, a member of the S&P 500 Index, is the nation’s largest producer of construction aggregates, a major producer of asphalt mix and concrete, and a leading producer of cement in Florida. Exhibit 6.15 presents Vulcan’s summarized income statement. In Note 2 to the consolidated financial statements, ‘‘Discontinued Operations,’’ Vulcan describes a June 2005 sale of substantially all assets of its chemicals business, known as Vulcan Chemicals, to Basic Chemicals, a subsidiary of Occidental Chemical Corporation. Basic Chemicals assumed certain liabilities relating to the chemicals business, including the obligation to monitor and remediate all releases of hazardous materials at or from the Wichita, Geismar, and Port Edwards plant facilities. The decision to sell the chemicals business was based on Vulcan’s desire to focus its resources on the construction materials business. The amounts reported as discontinued operations are not revenues and expenses from Vulcan operating the discontinued segment. Instead, the amounts represent a continual updating of the amount payable by the segment buyer. The receivable held by Vulcan from the sale is dependent on the levels of gas and chemical prices through the end of 2012. Vulcan classifies this financial instrument as a derivative contract that must be marked to market. The derivative does not hedge an existing transaction; therefore, its value changes are reflected in income as part of discontinued operations. As of 2008, Vulcan reported that final gains on disposal (if any) would occur after December 31, 2008. Goodwill impairment relates to Vulcan’s cement segment. Vulcan explains the need for the impairment as arising from the need to increase discount rates due to disruptions in credit markets as well as weak levels of construction activity. REQUIRED b. Prepare common-size income statements for Vulcan Materials. Interpret changes in profit margin over the three-year period in light of the special items. Round percentages to one decimal point.