i am trying to figure out how to do a vertical analysis from 2015 to 2017

(in thousands, except per share data) 2017 2016 2015 Net sales $ 4,323,668 $ 3,156,428 $ 2,306,458 Cost of sales 2,782,721 1,940,706 1,405,426 Gross profit 1,540,947 1,215,722 901,032 Selling, delivery and administrative expenses 1,444,768 1,087,863 802,888 Income from operations 96,179 127,859 98,144 Interest expense, net 41,869 36,325 28,915 Other income (expense), net (4,197) 1,870 (3,576) Gain (loss) on exchange transactions 12,893 (692) 8,807 Gain on sale of business - - 22,651 Bargain purchase gain, net of tax of $1,265 - - 2,011 Income before taxes 63,006 92,712 99,122 Income tax expense (benefit) (39,841) 36,049 34,078 Net income 102,847 56,663 65,044 Less: Net income attributable to noncontrolling interest 6,312 6,517 6,042 Net income attributable to Coca-Cola Bottling Co. Consolidated $ 96,535 $ 50,146 $ 59,002