What was the change in net income between Three Months Ended  June and September?
{"2019: -- Operating revenues": {"March 31,": 1813.4, "June 30,": 1889.6, "September 30,": 1953.6, "December 31,": 1923.7, "Year Ended, December 31,": 7580.3}, "2019: -- Costs of operations (1)": {"March 31,": 543.4, "June 30,": 563.3, "September 30,": 559.9, "December 31,": 550.2, "Year Ended, December 31,": 2216.8}, "2019: -- Operating income": {"March 31,": 614.9, "June 30,": 683.9, "September 30,": 728.3, "December 31,": 661.3, "Year Ended, December 31,": 2688.4}, "2019: -- Net income": {"March 31,": 407.6, "June 30,": 434.3, "September 30,": 505.3, "December 31,": 569.4, "Year Ended, December 31,": 1916.6}, "2019: -- Net income attributable to American Tower Corporation stockholders": {"March 31,": 397.4, "June 30,": 429.1, "September 30,": 498.6, "December 31,": 562.7, "Year Ended, December 31,": 1887.8}, "2019: -- Net income attributable to American Tower Corporation common stockholders": {"March 31,": 397.4, "June 30,": 429.1, "September 30,": 498.6, "December 31,": 562.7, "Year Ended, December 31,": 1887.8}, "2019: -- Basic net income per share attributable to American Tower Corporation common stockholders": {"March 31,": 0.9, "June 30,": 0.97, "September 30,": 1.13, "December 31,": 1.27, "Year Ended, December 31,": 4.27}, "2019: -- Diluted net income per share attributable to American Tower Corporation common stockholders": {"March 31,": 0.89, "June 30,": 0.96, "September 30,": 1.12, "December 31,": 1.26, "Year Ended, December 31,": 4.24}}
net_income_sep = df["2019: -- Net income"]["September 30,"]
net_income_jun = df["2019: -- Net income"]["June 30,"]
answer = net_income_sep - net_income_jun