What was the percentage change in the total revenue between 2018 and 2019?
{"Merchant fees": {"2019": 361755, "2018": 297776, "2017": 234548}, "Interchange fees": {"2019": 44150, "2018": 51128, "2017": 44410}, "Transaction fees": {"2019": 405905, "2018": 348904, "2017": 278958}, "Servicing fees(1)": {"2019": 123697, "2018": 65597, "2017": 46575}, "Other(2)": {"2019": 44, "2018": 172, "2017": 354}, "Servicing and other": {"2019": 123741, "2018": 65769, "2017": 46929}, "Total revenue": {"2019": 529646, "2018": 414673, "2017": 325887}}
total_revenue_2019 = df["Total revenue"]["2019"]
total_revenue_2018 = df["Total revenue"]["2018"]
answer = ( total_revenue_2019 - total_revenue_2018 ) / total_revenue_2018 * 100.0