Nucor Corporation produces steel and steel products at its eight mills and is a major recycler of scrap metal. The following data relate to Nucor for four years. In 2017, Nucor's net income was higher by $175.2 million because of a one-time effect of the Tax Cuts and Jobs Act. 2016 $15, 223.5 Nucor Corporation in millions) Total assets Common stockholders' equity Total debt Sales Net income Interest expense Assumed marginal income tax rate 2015 $14,327.0 7.849.9 4,388.5 4,357.1 16,200.1 900.4 169.2 0.37 2017 $15,041.3 9,084.8 3,795.1 20,252.4 1,380.6 173.6 0.37 2018 $17,920.6 10,202.0 4,291.1 25,067.3 2,481.1 135.5 0.23 Source: Nucor Form 10-Ks for 2015-2018. Required: In the following analyses, eliminate the one-time net income effect of the Tax Cuts and Jobs Act on 2017's results. 1. Calculate Nucor's ROA for 2016, 2017, and 2018. 2. Decompose ROA into operating profit margin and asset turnover components. 3. Has Nucor's profitability changed over the three years? 4. Calculate the rate of return on common stockholders' equity for 2016, 2017 and 2018