Compute the vertical analysis for HEB Income Statement. Explain the relationship between net sales and cost of sales. What can you conclude?

\begin{tabular}{|c|c|c|c|} \hline Twelve Months Ended (In millions) & Jan. 29, 2016 & Jan. 30,2015 & Jan. 31,2014 \\ \hline & $59,074 & $56,223 & $53,417 \\ \hline Cost of sales. . . . . . . . . . . . . . & 38,504 & 36,665 & 34,941 \\ \hline \begin{tabular}{l} Gross margin \\ Expenses: \end{tabular} & 20,570 & 19,558 & 18,476 \\ \hline Selling, general and administrative & 14,115 & 13,281 & 12,865 \\ \hline Depreciation & 1,484 & 1,485 & 1,462 \\ \hline Interest - net & 552 & 516 & 476 \\ \hline Total expenses... & 16,151 & 15,282 & 14,803 \\ \hline Pre-tax earnings........ & 4,419 & 4,276 & 3,673 \\ \hline Income tax provision & 1,873 & 1,578 & 1,387 \\ \hline Net earnings. & $2,546 & $2,698 & $2,286 \\ \hline \end{tabular}