What is the percentage change in revenue from 2018 to 2019?
{"Year Ended December 31, -- ": {"2019": 2019, "2018": 2018}, "(In thousands) -- Revenues": {"2019": 6490, "2018": 7859}, "(In thousands) -- (Loss) from operations": {"2019": -7488, "2018": -6322}, "(In thousands) -- (Loss) from operations as a % of revenues": {"2019": -115, "2018": -80}}
revenue_2019 = df["(In thousands) -- Revenues"]["2019"]
revenue_2018 = df["(In thousands) -- Revenues"]["2018"]
answer = (revenue_2019 - revenue_2018) / revenue_2018 * 100.0