What was the difference in total margin comparing fiscal 2019 and 2018?
{"Hardware Revenues: -- Americas": {"2019": 1889, "Actual": -6, "Constant": -4, "2018": 2003}, "Hardware Revenues: -- EMEA": {"2019": 1082, "Actual": -10, "Constant": -5, "2018": 1201}, "Hardware Revenues: -- Asia Pacific": {"2019": 733, "Actual": -7, "Constant": -4, "2018": 790}, "Hardware Revenues: -- Total revenues": {"2019": 3704, "Actual": -7, "Constant": -5, "2018": 3994}, "Expenses: -- Hardware products and support (1)": {"2019": 1327, "Actual": -14, "Constant": -11, "2018": 1547}, "Expenses: -- Sales and marketing (1)": {"2019": 520, "Actual": -19, "Constant": -16, "2018": 643}, "Expenses: -- Total expenses (1)": {"2019": 1847, "Actual": -16, "Constant": -13, "2018": 2190}, "Expenses: -- Total Margin": {"2019": 1857, "Actual": 3, "Constant": 6, "2018": 1804}, "Expenses: -- Total Margin %": {"2019": 50, "Actual": "", "Constant": "", "2018": 45}, "% Revenues by Geography: -- Americas": {"2019": 51, "Actual": "", "Constant": "", "2018": 50}, "% Revenues by Geography: -- EMEA": {"2019": 29, "Actual": "", "Constant": "", "2018": 30}, "% Revenues by Geography: -- Asia Pacific": {"2019": 20, "Actual": "", "Constant": "", "2018": 20}}
total_margin_2019 = df["Expenses: -- Total Margin"]["2019"]
total_margin_2018 = df["Expenses: -- Total Margin"]["2018"]
answer = total_margin_2019 - total_margin_2018