What was the change in gross carrying amount between the 2021 and 2022 Notes?
{"2021 Notes": {"Gross Carrying Amount": 650, "Unamortized Discount and Deferred Financing Costs": -2, "Net Carrying Amount": 648}, "2022 Notes": {"Gross Carrying Amount": 400, "Unamortized Discount and Deferred Financing Costs": -2, "Net Carrying Amount": 398}, "2026 Notes": {"Gross Carrying Amount": 850, "Unamortized Discount and Deferred Financing Costs": -7, "Net Carrying Amount": 843}, "2027 Notes": {"Gross Carrying Amount": 400, "Unamortized Discount and Deferred Financing Costs": -5, "Net Carrying Amount": 395}, "2047 Notes": {"Gross Carrying Amount": 400, "Unamortized Discount and Deferred Financing Costs": -9, "Net Carrying Amount": 391}, "Total debt": {"Gross Carrying Amount": 2700, "Unamortized Discount and Deferred Financing Costs": -25, "Net Carrying Amount": 2675}}
gross_carrying_amount_2021 = df["2021 Notes"]["Gross Carrying Amount"]
gross_carrying_amount_2022 = df["2022 Notes"]["Gross Carrying Amount"]
answer = gross_carrying_amount_2021 - gross_carrying_amount_2022