What was the percentage change in the total Mortgage loan originations between 2018 and 2019?
{"Mortgage loan originations(1): -- Purchase": {"2019": 1272.0, "2018": 1185.0, "2017": 1143.0}, "Mortgage loan originations(1): -- Refinance": {"2019": 796.0, "2018": 458.0, "2017": 616.0}, "Mortgage loan originations(1): -- Total": {"2019": 2068.0, "2018": 1643.0, "2017": 1760.0}}
total_2019 = df["Mortgage loan originations(1): -- Total"]["2019"]
total_2018 = df["Mortgage loan originations(1): -- Total"]["2018"]
answer = (total_2019 - total_2018) / total_2018 * 100.0