What is the percentage change in the ending balance between 2018 and 2019?
{"Beginning balance, January 1": {"2019": 2429, "2018": 7478, "2017": 3532}, "Additions and adjustments": {"2019": 1074, "2018": 1691, "2017": 7680}, "Write-offs": {"2019": -2128, "2018": -6740, "2017": -3734}, "Ending balance, December 31": {"2019": 1375, "2018": 2429, "2017": 7478}}
ending_balance_2019 = df["Ending balance, December 31"]["2019"]
beginning_balance_2019 = df["Beginning balance, January 1"]["2019"]
answer = (ending_balance_2019 - beginning_balance_2019) / beginning_balance_2019 * 100.0