What is the change in Total Operating Expenses from 2018 to 2019?
{"Cost of services ": {"2019": 15884.0, "2018": 15335.0, "2019 vs. 2018": 549.0, "": 3.6}, "Cost of wireless equipment ": {"2019": 18219.0, "2018": 18763.0, "2019 vs. 2018": -544.0, "": -2.9}, "Selling, general and administrative expense ": {"2019": 16639.0, "2018": 15701.0, "2019 vs. 2018": 938.0, "": 6.0}, "Depreciation and amortization expense ": {"2019": 11353.0, "2018": 11952.0, "2019 vs. 2018": -599.0, "": -5.0}, "Total Operating Expenses ": {"2019": 62095.0, "2018": 61751.0, "2019 vs. 2018": 344.0, "": 0.6}}
total_operating_expenses_2019 = df["Total Operating Expenses "]["2019"]
total_operating_expenses_2018 = df["Total Operating Expenses "]["2018"]
answer = total_operating_expenses_2019 - total_operating_expenses_2018