What was the change in Employee separation costs between 2017 and 2018?
{"Restructuring -- Employee separation costs": {"2019": 65.3, "2018": 1.2, "2017": 39.1}, "Restructuring -- Gain on sale of assets": {"2019": "\u2014", "2018": -4.4, "2017": "\u2014"}, "Restructuring -- Impairment charges": {"2019": 3.6, "2018": "\u2014", "2017": 12.6}, "Restructuring -- Contract exit costs": {"2019": -4.7, "2018": 0.7, "2017": 44.1}, "Restructuring -- Other": {"2019": -0.3, "2018": "\u2014", "2017": 2.8}, "Restructuring -- Legal contingencies": {"2019": -30.2, "2018": "\u2014", "2017": "\u2014"}, "Restructuring -- Non-restructuring contract exit costs and other": {"2019": "\u2014", "2018": 20.0, "2017": "\u2014"}, "Restructuring -- Total": {"2019": 33.7, "2018": 17.5, "2017": 98.6}}
employee_separation_cost_2018 = df["Restructuring -- Employee separation costs"]["2018"]
employee_separation_cost_2017 = df["Restructuring -- Employee separation costs"]["2017"]
answer = employee_separation_cost_2018 - employee_separation_cost_2017