What was the percentage change in operating income between 2018 and 2019?
{"Net revenue": {"2019": 25282320.0, "2018": 22095416.0, "2017": 19063121.0}, "Gross profit": {"2019": 1913401.0, "2018": 1706792.0, "2017": 1545643.0}, "Operating income": {"2019": 701356.0, "2018": 542153.0, "2017": 410230.0}, "Net income attributable to Jabil Inc": {"2019": 287111.0, "2018": 86330.0, "2017": 129090.0}, "Earnings per share  basic": {"2019": 1.85, "2018": 0.5, "2017": 0.71}, "Earnings per share  diluted": {"2019": 1.81, "2018": 0.49, "2017": 0.69}}
operating_income_2019 = df["Operating income"]["2019"]
operating_income_2018 = df["Operating income"]["2018"]
answer = ( operating_income_2019 - operating_income_2018 ) / operating_income_2018 * 100.0