What was the change in Construction-in-progress between 2018 and 2019?
{"Towers": {"Estimated Useful Lives (years) (1)": 20.0, "December 31, 2019": 13930.7, "December 31, 2018": 12777.9}, "Equipment (2)": {"Estimated Useful Lives (years) (1)": 2.0, "December 31, 2019": 1897.3, "December 31, 2018": 1667.3}, "Buildings and improvements": {"Estimated Useful Lives (years) (1)": 3.0, "December 31, 2019": 638.9, "December 31, 2018": 628.5}, "Land and improvements (3)": {"Estimated Useful Lives (years) (1)": 20.0, "December 31, 2019": 2486.1, "December 31, 2018": 2285.4}, "Construction-in-progress": {"Estimated Useful Lives (years) (1)": "", "December 31, 2019": 372.6, "December 31, 2018": 358.1}, "Total": {"Estimated Useful Lives (years) (1)": "", "December 31, 2019": 19325.6, "December 31, 2018": 17717.2}, "Less accumulated depreciation": {"Estimated Useful Lives (years) (1)": "", "December 31, 2019": -7241.2, "December 31, 2018": -6470.1}, "Property and equipment, net": {"Estimated Useful Lives (years) (1)": "", "December 31, 2019": 12084.4, "December 31, 2018": 11247.1}}
construction_in_progress_december_31_2019 = df["Construction-in-progress"]["December 31, 2019"]
construction_in_progress_december_31_2018 = df["Construction-in-progress"]["December 31, 2018"]
answer = construction_in_progress_december_31_2019 - construction_in_progress_december_31_2018