What is the percentage change in total revenue between 2018 and 2019?
{"Revenue by product line (1) : -- New products": {"2019": 3123, "2018": 5735, "2017": 5853}, "Revenue by product line (1) : -- Mature products": {"2019": 7187, "2018": 6894, "2017": 6296}, "Revenue by product line (1) : -- Total revenue": {"2019": 10310, "2018": 12629, "2017": 12149}}
total_revenue_2019 = df["Revenue by product line (1) : -- Total revenue"]["2019"]
total_revenue_2018 = df["Revenue by product line (1) : -- Total revenue"]["2018"]
answer = (total_revenue_2019 - total_revenue_2018) / total_revenue_2018 * 100.0