What was the change in leasehold improvements between 2018 and 2019?
{"Furniture, fixtures and office equipment": {"2019": 5604, "2018": 4102}, "Computer software and hardware": {"2019": 17767, "2018": 16228}, "Internal-use software": {"2019": 8949, "2018": 5072}, "Construction in progress": {"2019": 4232, "2018": 3790}, "Leasehold improvements": {"2019": 23223, "2018": 18338}, "Real property": {"2019": 4917, "2018": 707}, "Land": {"2019": 1398, "2018": 508}, "Total property and equipment": {"2019": 66090, "2018": 48745}, "Accumulated depreciation": {"2019": -27542, "2018": -20988}}
leasehold_improvements_2019 = df["Leasehold improvements"]["2019"]
leasehold_improvements_2018 = df["Leasehold improvements"]["2018"]
answer = leasehold_improvements_2019 - leasehold_improvements_2018