What is the percentage change in the ending balance of allowance for doubtful accounts from 2018 to 2019?
{"Beginning balance": {"2019": 65542, "2018": 22173}, "Provision charged to expense": {"2019": 29849, "2018": 55152}, "Deductions": {"2019": -40352, "2018": -11783}, "Ending balance": {"2019": 55039, "2018": 65542}}
ending_balance_2019 = df["Ending balance"]["2019"]
beginning_balance_2019 = df["Beginning balance"]["2019"]
answer = (ending_balance_2019 - beginning_balance_2019) / beginning_balance_2019 * 100.0