Common-size and trend percentages for a company's net sales, cost of goods sold, and expenses follow: Net sales Cost of goods sold Expenses Common-Size Percentages 2020 2019 2018 100.0% 100.0% 100.0% 64.8 61.7 58.4 13.5 11.9 13.0 Trend Percentages 2020 2019 2018 108.8% 107.1% 100.0% 115.6 110.3 100.0 109.7 103.7 100.0 Required: a. Calculate the profit percentage for 2018, 2019 and 2020. (Round the final answers to 2 decimal places.) 2018 2019 2020 Profit Percentage % % % b. Determine whether the company's profit increased, decreased, or remained unchanged during this three-year period. Profit