What is the change in total net revenue from 2019 to 2018?
{"Net revenue by product family (1): -- Architecture, Engineering and Construction": {"2019": 1021.6, "2018": 787.5, "2017": 810.4}, "Net revenue by product family (1): -- Manufacturing": {"2019": 616.2, "2018": 528.8, "2017": 575.2}, "Net revenue by product family (1): -- AutoCAD and AutoCAD LT": {"2019": 731.8, "2018": 561.4, "2017": 472.7}, "Net revenue by product family (1): -- Media and Entertainment": {"2019": 182.0, "2018": 152.1, "2017": 138.8}, "Net revenue by product family (1): -- Other": {"2019": 18.2, "2018": 26.8, "2017": 33.9}, "Net revenue by product family (1): -- Total net revenue": {"2019": 2569.8, "2018": 2056.6, "2017": 2031.0}, "Americas -- U.S.": {"2019": 874.6, "2018": 740.4, "2017": 742.1}, "Americas -- Other Americas": {"2019": 175.3, "2018": 130.7, "2017": 129.8}, "Americas -- Total Americas": {"2019": 1049.9, "2018": 871.1, "2017": 871.9}, "Americas -- Europe, Middle East and Africa": {"2019": 1034.3, "2018": 815.4, "2017": 800.4}, "Americas -- Asia Pacific": {"2019": 485.6, "2018": 370.1, "2017": 358.7}, "Americas -- Total net revenue": {"2019": 2569.8, "2018": 2056.6, "2017": 2031.0}, "Net revenue by sales channel: -- Indirect": {"2019": 1830.8, "2018": 1443.8, "2017": 1468.9}, "Net revenue by sales channel: -- Direct": {"2019": 739.0, "2018": 612.8, "2017": 562.1}, "Net revenue by sales channel: -- Total net revenue": {"2019": 2569.8, "2018": 2056.6, "2017": 2031.0}}
total_net_revenue_2019 = df["Net revenue by product family (1): -- Total net revenue"]["2019"]
total_net_revenue_2018 = df["Net revenue by product family (1): -- Total net revenue"]["2018"]
answer = total_net_revenue_2019 - total_net_revenue_2018