What was the percentage change in operating revenues between Three Months Ended  September and December?
{"2018: -- Operating revenues": {"March 31,": 1741.8, "June 30,": 1780.9, "September 30,": 1785.5, "December 31,": 2131.9, "Year Ended December 31,": 7440.1}, "2018: -- Costs of operations (1)": {"March 31,": 519.9, "June 30,": 560.3, "September 30,": 556.7, "December 31,": 540.9, "Year Ended December 31,": 2177.8}, "2018: -- Operating income": {"March 31,": 402.9, "June 30,": 546.0, "September 30,": 567.2, "December 31,": 388.9, "Year Ended December 31,": 1905.0}, "2018: -- Net income": {"March 31,": 280.3, "June 30,": 314.4, "September 30,": 377.3, "December 31,": 292.7, "Year Ended December 31,": 1264.7}, "2018: -- Net income attributable to American Tower Corporation stockholders": {"March 31,": 285.2, "June 30,": 306.7, "September 30,": 366.9, "December 31,": 277.6, "Year Ended December 31,": 1236.4}, "2018: -- Dividends on preferred stock": {"March 31,": -9.4, "June 30,": "\u2014", "September 30,": "\u2014", "December 31,": "\u2014", "Year Ended December 31,": -9.4}, "2018: -- Net income attributable to American Tower Corporation common stockholders": {"March 31,": 275.8, "June 30,": 306.7, "September 30,": 366.9, "December 31,": 277.6, "Year Ended December 31,": 1227.0}, "2018: -- Basic net income per share attributable to American Tower Corporation common stockholders": {"March 31,": 0.63, "June 30,": 0.69, "September 30,": 0.83, "December 31,": 0.63, "Year Ended December 31,": 2.79}, "2018: -- Diluted net income per share attributable to American Tower Corporation common stockholders": {"March 31,": 0.63, "June 30,": 0.69, "September 30,": 0.83, "December 31,": 0.62, "Year Ended December 31,": 2.77}}
revenue_2018_dec = df["2018: -- Operating revenues"]["December 31,"]
revenue_2018_sep = df["2018: -- Operating revenues"]["September 30,"]
answer = (revenue_2018_dec - revenue_2018_sep) / revenue_2018_sep * 100.0