What was the change in interest cost in 2019 from 2018?
{"Service cost": {"2019": 405, "2018": 448, "2017": 443}, "Interest cost": {"2019": 254, "2018": 196, "2017": 194}, "Recognized actuarial (gains)": {"2019": -86, "2018": -58, "2017": -43}, "Net periodic benefit cost": {"2019": 573, "2018": 586, "2017": 594}, "Unrealized net actuarial (gains), net of tax": {"2019": -2324, "2018": -2256, "2017": -1574}, "Total amount recognized in net periodic benefit cost and accumulated other comprehensive income (loss)": {"2019": -1751, "2018": -1670, "2017": -980}}
interest_cost_2019 = df["Interest cost"]["2019"]
interest_cost_2018 = df["Interest cost"]["2018"]
answer = interest_cost_2019 - interest_cost_2018