What is the percentage change in the cost of goods sold from operations in 2018 and 2019?
{"": {"2019": "(in thousands)", "2018": "", "%": ""}, "Revenues": {"2019": 23713.0, "2018": 14762.0, "%": 60.6}, "Cost of goods sold": {"2019": 24574.0, "2018": 11780.0, "%": -108.6}, "Gross profit (loss)": {"2019": -861, "2018": 2982, "%": ""}, "Gross profit %": {"2019": -3.6, "2018": 20.2, "%": ""}, "Selling, general and administrative expenses": {"2019": 13696.0, "2018": 11194.0, "%": -22.4}, "Loss from operations": {"2019": -14557.0, "2018": -8212.0, "%": -77.3}, "Other income (expense):": {"2019": -96, "2018": -12, "%": ""}, "Interest expense": {"2019": 50, "2018": "-", "%": ""}, "Other, net": {"2019": 868, "2018": 168, "%": ""}, "Total other (expense) income": {"2019": 822, "2018": 156, "%": ""}, "Loss before income taxes": {"2019": -13735, "2018": -8056, "%": ""}}
cost_of_goods_sold_2019 = df["Cost of goods sold"]["2019"]
cost_of_goods_sold_2018 = df["Cost of goods sold"]["2018"]
answer = ( cost_of_goods_sold_2019 - cost_of_goods_sold_2018 ) / cost_of_goods_sold_2018 * 100.0