What was the change in Revenue in 2019 from 2018?
{"": {"FY19": "$M", "FY18": "$M", "Change": "%"}, "Statutory measures -- Revenue": {"FY19": 710.6, "FY18": 639.0, "Change": 11.2}, "Statutory measures -- Profit / (Loss) before taxation": {"FY19": 53.6, "FY18": -41.0, "Change": "nm"}, "Statutory measures -- Net cash flow from operating activities": {"FY19": 142.9, "FY18": 147.7, "Change": -3.2}, "Alternative performance measures2 -- Billings": {"FY19": 760.3, "FY18": 768.6, "Change": -1.1}, "Alternative performance measures2 -- Cash EBITDA": {"FY19": 167.9, "FY18": 199.2, "Change": -15.7}, "Alternative performance measures2 -- Adjusted operating profit": {"FY19": 109.0, "FY18": 58.3, "Change": 87.0}, "Alternative performance measures2 -- Unlevered free cash flow": {"FY19": 123.8, "FY18": 139.6, "Change": -11.3}}
statutory_measures__Revenue_FY19 = df["Statutory measures -- Revenue"]["FY19"]
statutory_measures__Revenue_FY18 = df["Statutory measures -- Revenue"]["FY18"]
answer = statutory_measures__Revenue_FY19 - statutory_measures__Revenue_FY18