What is the change in Net carrying amount from December 31, 2019 to December 31, 2018?
{"Liability component: -- Principal": {"2019": 92000, "2018": 115000}, "Liability component: -- Less: debt discount, net of amortization": {"2019": -12776, "2018": -20903}, "Liability component: -- Net carrying amount": {"2019": 79224, "2018": 94097}, "Liability component: -- Equity component (1)": {"2019": -14555, "2018": 22094}}
net_carrying_amount_2019 = df["Liability component: -- Net carrying amount"]["2019"]
net_carrying_amount_2018 = df["Liability component: -- Net carrying amount"]["2018"]
answer = net_carrying_amount_2019 - net_carrying_amount_2018