What was the change in the ending balance between 2017 and 2019?
{"Beginning balance": {"2019": 2876, "2018": 73606, "2017": 41268}, "Additions": {"2019": 157928, "2018": 93240, "2017": 134659}, "Proceeds from sales and borrower payments(1)": {"2019": -104858, "2018": -161009, "2017": -93044}, "Loss on sale": {"2019": "\u2014", "2018": "\u2014", "2017": -500}, "Increase in valuation allowance": {"2019": -1289, "2018": -92, "2017": -584}, "Transfers(2)": {"2019": 251, "2018": 22, "2017": -5017}, "Write offs and other(3)": {"2019": -2982, "2018": -2891, "2017": -3176}, "Ending balance": {"2019": 51926, "2018": 2876, "2017": 73606}}
ending_balance_2019 = df["Ending balance"]["2019"]
beginning_balance_2018 = df["Beginning balance"]["2018"]
answer = ending_balance_2019 - beginning_balance_2018