What was the change in prepaid insurance in 2019 from 2018?
{"Prepaid maintenance": {"2019": 6218, "2018": 5888}, "Prepaid insurance": {"2019": 5321, "2018": 4500}, "Prepaid software": {"2019": 4236, "2018": 3499}, "Prepaid rent": {"2019": 421, "2018": 3471}, "Prepaid other": {"2019": 4672, "2018": 6396}, "": {"2019": 20868, "2018": 23754}}
prepaid_insurance_2019 = df["Prepaid insurance"]["2019"]
prepaid_insurance_2018 = df["Prepaid insurance"]["2018"]
answer = prepaid_insurance_2019 - prepaid_insurance_2018