What is the change in Inventories: Finished goods from year ended December 31, 2018 to 2019?
{"Inventories: -- Raw materials": {"December 31, 2019": 138.4, "December 31, 2018": 137.3}, "Inventories: -- Work in process": {"December 31, 2019": 772.9, "December 31, 2018": 760.7}, "Inventories: -- Finished goods": {"December 31, 2019": 321.1, "December 31, 2018": 327.2}, "Inventories: -- ": {"December 31, 2019": 1232.4, "December 31, 2018": 1225.2}, "Property, plant and equipment, net: -- Land": {"December 31, 2019": 125.2, "December 31, 2018": 125.5}, "Property, plant and equipment, net: -- Buildings": {"December 31, 2019": 860.6, "December 31, 2018": 820.4}, "Property, plant and equipment, net: -- Machinery and equipment": {"December 31, 2019": 4275.2, "December 31, 2018": 3980.2}, "Property, plant and equipment, net: -- Property, plant and equipment, gross": {"December 31, 2019": 5261.0, "December 31, 2018": 4926.1}, "Property, plant and equipment, net: -- Less: Accumulated depreciation": {"December 31, 2019": -2669.4, "December 31, 2018": -2376.5}, "Property, plant and equipment, net: -- ": {"December 31, 2019": 2591.6, "December 31, 2018": 2549.6}, "Accrued expenses: -- Accrued payroll and related benefits": {"December 31, 2019": 153.4, "December 31, 2018": 240.8}, "Accrued expenses: -- Sales related reserves": {"December 31, 2019": 247.3, "December 31, 2018": 294.8}, "Accrued expenses: -- Income taxes payable": {"December 31, 2019": 22.5, "December 31, 2018": 38.2}, "Accrued expenses: -- Other": {"December 31, 2019": 115.6, "December 31, 2018": 85.3}, "Accrued expenses: -- ": {"December 31, 2019": 538.8, "December 31, 2018": 659.1}}
inventories_finished_goods_december_31_2019 = df["Inventories: -- Finished goods"]["December 31, 2019"]
inventories_finished_goods_december_31_2018 = df["Inventories: -- Finished goods"]["December 31, 2018"]
answer = inventories_finished_goods_december_31_2019 - inventories_finished_goods_december_31_2018