Following is Stanley's income statement for the year (in millions): STANLEY INC. Income Statement For the year ended December 31 ($ millions) Sales $11,406.9 Cost of goods sold 7,139.7 Gross profit 4,267.2 Selling, general and administrative expenses 2,602.0 Other operating expenses 268.2 Operating income 1,397.0 Interest and other nonoperating expenses 171.3 Income before income tax 1,225.7 Income tax expense 261.2 Net income $964.5 Compute Stanley's gross profit margin.