What was the change in net earnings between 2017 and 2018?
{"Revenues": {"2019": 1177.2, "2018": 1114.0, "2017": 1051.6}, "Adjusted Revenues(1)": {"2019": 1177.7, "2018": 1116.5, "2017": 1056.1}, "Earnings before equity in losses of unconsolidated affiliates": {"2019": 182.8, "2018": 168.5, "2017": 254.2}, "Net earnings(2)": {"2019": 108.8, "2018": 168.5, "2017": 254.2}, "Net earnings margin": {"2019": 9.2, "2018": 15.1, "2017": 24.2}, "Net earnings attributable to Black Knight": {"2019": 108.8, "2018": 168.5, "2017": 182.3}, "Net earnings attributable to Black Knight, per diluted share": {"2019": 0.73, "2018": 1.14, "2017": 1.47}, "Adjusted Net Earnings(1)": {"2019": 295.4, "2018": 277.9, "2017": 209.6}, "Adjusted EPS(1)": {"2019": 1.99, "2018": 1.87, "2017": 1.38}, "Adjusted EBITDA(1)": {"2019": 583.4, "2018": 542.5, "2017": 505.8}, "Adjusted EBITDA Margin(1)": {"2019": 49.5, "2018": 48.6, "2017": 47.9}}
net_earnings_2018 = df["Earnings before equity in losses of unconsolidated affiliates"]["2018"]
net_earnings_2017 = df["Earnings before equity in losses of unconsolidated affiliates"]["2017"]
answer = net_earnings_2018 - net_earnings_2017