What percentage of total Global Business Services external revenue was Application Management in 2018?
{"($ in millions) -- For the year ended December 31:": {"2018": 2018, "2017": 2017, "Yr.-to-Yr. Percent Change": "Yr.-to-Yr. Percent Change", "Yr.-to-Yr. Percent Change Adjusted for Currency": "Yr.-to-Yr. Percent Change Adjusted for Currency"}, "($ in millions) -- Global Business Services external revenue": {"2018": 16595.0, "2017": 16073.0, "Yr.-to-Yr. Percent Change": 3.2, "Yr.-to-Yr. Percent Change Adjusted for Currency": 2.3}, "($ in millions) -- Consulting": {"2018": 7705.0, "2017": 7262.0, "Yr.-to-Yr. Percent Change": 6.1, "Yr.-to-Yr. Percent Change Adjusted for Currency": 5.1}, "($ in millions) -- Application Management": {"2018": 7852.0, "2017": 7821.0, "Yr.-to-Yr. Percent Change": 0.4, "Yr.-to-Yr. Percent Change Adjusted for Currency": -0.5}, "($ in millions) -- Global Process Services": {"2018": 1037.0, "2017": 990.0, "Yr.-to-Yr. Percent Change": 4.8, "Yr.-to-Yr. Percent Change Adjusted for Currency": 4.7}}
consulting_revenue_2018 = df["($ in millions) -- Consulting"]["2018"]
total_revenue_2018 = df["($ in millions) -- Global Business Services external revenue"]["2018"]
answer = consulting_revenue_2018 / total_revenue_2018 * 100.0