What is the change in finished goods between 2018 and 2019?
{"Ingredients": {"2019": 1942, "2018": 1580}, "Packaging": {"2019": 2230, "2018": 2072}, "Finished goods": {"2019": 2220, "2018": 2165}, "Total inventories, net": {"2019": 6392, "2018": 5817}}
finished_goods_2019 = df["Finished goods"]["2019"]
finished_goods_2018 = df["Finished goods"]["2018"]
answer = finished_goods_2019 - finished_goods_2018