What is the increase / (decrease) in revenue from 2018 to 2019?
{"Orders": {"2019": 5806.0, "2018": 5569.0, "Actual": 4.0, "Comp.": 3.0}, "Revenue": {"2019": 5526.0, "2018": 4930.0, "Actual": 12.0, "Comp.": 11.0}, "Adjusted EBITA": {"2019": -71.0, "2018": -305.0, "Actual": 77, "Comp.": ""}, "Adjusted EBITA margin": {"2019": -1.3, "2018": -6.2, "Actual": "", "Comp.": ""}}
revenue_2019 = df["Revenue"]["2019"]
revenue_2018 = df["Revenue"]["2018"]
answer = revenue_2019 - revenue_2018