What is the percentage change in the total revenue from 2018 to 2019?
{"Revenue (in millions)": {"June 30, 2019": 9654, "June 24, 2018": 11077, "June 25, 2017": 8014}, "Korea": {"June 30, 2019": 23, "June 24, 2018": 35, "June 25, 2017": 31}, "China": {"June 30, 2019": 22, "June 24, 2018": 16, "June 25, 2017": 13}, "Japan": {"June 30, 2019": 20, "June 24, 2018": 17, "June 25, 2017": 13}, "Taiwan": {"June 30, 2019": 17, "June 24, 2018": 13, "June 25, 2017": 26}, "UnitedStates": {"June 30, 2019": 8, "June 24, 2018": 7, "June 25, 2017": 8}, "SoutheastAsia": {"June 30, 2019": 6, "June 24, 2018": 7, "June 25, 2017": 5}, "Europe": {"June 30, 2019": 4, "June 24, 2018": 5, "June 25, 2017": 4}}
revenue_2019 = df["Revenue (in millions)"]["June 30, 2019"]
revenue_2018 = df["Revenue (in millions)"]["June 24, 2018"]
answer = (revenue_2019 - revenue_2018) / revenue_2018 * 100.0