What was the change in payments made to third-party software developers between 2018 and 2019?
{"Internally-developed software costs": {"2019": 345, "2018": 291}, "Payments made to third-party software developers": {"2019": 31, "2018": 38}, "Total software development costs": {"2019": 376, "2018": 329}}
payments_made_to_thirdparty_software_developers_2019 = df["Payments made to third-party software developers"]["2019"]
payments_made_to_thirdparty_software_developers_2018 = df["Payments made to third-party software developers"]["2018"]
answer = payments_made_to_thirdparty_software_developers_2019 - payments_made_to_thirdparty_software_developers_2018