What was the change in the interest expense between 2017 and 2018?
{"Net income": {"2019": 95973, "2018": 127980, "2017": 138668}, "Interest expense": {"2019": 23860, "2018": 23584, "2017": 7536}, "Tax expense (benefit)": {"2019": -7125, "2018": 5534, "2017": "\u2014"}, "Depreciation and amortization": {"2019": 7304, "2018": 4478, "2017": 3983}, "Equity-based compensation expense(1)": {"2019": 13769, "2018": 6054, "2017": 4253}, "Change in financial guarantee liability(2)": {"2019": 16215, "2018": "\u2014", "2017": "\u2014"}, "Transaction expenses(3)": {"2019": 11345, "2018": 2393, "2017": 2612}, "Non-recurring expenses(4)": {"2019": 2804, "2018": "\u2014", "2017": "\u2014"}, "Adjusted EBITDA": {"2019": 164145, "2018": 170023, "2017": 157052}}
interest_expense_2018 = df["Interest expense"]["2018"]
interest_expense_2017 = df["Interest expense"]["2017"]
answer = interest_expense_2018 - interest_expense_2017