What was the difference in total expenses in 2019 and 2017?
{"Year Ended May 31, -- (in millions)": {"2019": 2019, "2018": 2018, "2017": 2017}, "Cloud and license: -- revenues (1)": {"2019": 32582, "2018": 32041, "2017": 30452}, "Cloud and license: -- Cloud services and license support expenses": {"2019": 3597, "2018": 3441, "2017": 2881}, "Cloud and license: -- Sales and marketing expenses": {"2019": 7398, "2018": 7213, "2017": 6770}, "Cloud and license: -- Margin (2)": {"2019": 21587, "2018": 21387, "2017": 20801}, "Hardware: -- revenues": {"2019": 3704, "2018": 3994, "2017": 4152}, "Hardware: -- Hardware products and support expenses": {"2019": 1327, "2018": 1547, "2017": 1618}, "Hardware: -- Sales and marketing expenses": {"2019": 520, "2018": 643, "2017": 825}, "Hardware: -- Margin (2)": {"2019": 1857, "2018": 1804, "2017": 1709}, "Services: -- revenues": {"2019": 3240, "2018": 3395, "2017": 3359}, "Services: -- Services expenses": {"2019": 2703, "2018": 2729, "2017": 2661}, "Services: -- Margin (2)": {"2019": 537, "2018": 666, "2017": 698}, "Totals: -- revenues (1)": {"2019": 39526, "2018": 39430, "2017": 37963}, "Totals: -- Expenses": {"2019": 15545, "2018": 15573, "2017": 14755}, "Totals: -- Margin (2)": {"2019": 23981, "2018": 23857, "2017": 23208}}
total_expenses_2019 = df["Totals: -- Expenses"]["2019"]
total_expenses_2017 = df["Totals: -- Expenses"]["2017"]
answer = total_expenses_2019 - total_expenses_2017