Fiscal Year Ended December 31 2018 2019 2017 (in thousands) Gross sales $2,004,719 $1,937,021 $1,835,987 Less: Sales discounts 4,649 4,811 4,406 Less: Sales returns and allowances 2,406 2,324 2,203 Net sales $1,997,502 $1,930,048 $1,829,378 Cost of goods sold 621,463 619,847 660,955 Gross profit $1,376,039 $1,310,201 $1,168,423 Operating expenses 577,369 595,226 583,555 Operating income $798,670 $714,975 $584,868 Other income (expenses) (5,510) (8,773) 15,973 $814,643 $709,465 $576,095 Net income At December 31 2019 2018 2017 (in thousands) $201,290 $195,427 $182,642 Accounts receivable Less: Allowance for doubtful accounts 2,516 2,736 2,192 $198,774 $192,691 $180,450 Net accounts receivable Required: 1. Calculate the following ratios for 2018 and 2019. Round your answers to two decimal places 2018 2019 a. Gross profit margin 68.89 % 67.88 39.98 % b. Operating margin 37.04 c. Net profit margin 40.78 % 36.76 d. Accounts receivable turnover 2. Are operations improving or worsening