What is the change in Finished Goods between December 31, 2018 and 2019?
{"Finished Goods": {"2019": 8320, "2018": 12472}, "Work in process": {"2019": "\u2014", "2018": 67}, "Component parts": {"2019": 6768, "2018": 4716}, "Service parts": {"2019": 4238, "2018": 5482}, "": {"2019": 19326, "2018": 22737}}
finished_goods_2019 = df["Finished Goods"]["2019"]
finished_goods_2018 = df["Finished Goods"]["2018"]
answer = finished_goods_2019 - finished_goods_2018