What is the change between capital expenditure in 2019 and 2018?
{"Capital expenditures 20172019 -- SEKbillion": {"2019": 2019.0, "2018": 2018.0, "2017": 2017.0}, "Capital expenditures 20172019 -- Capital expenditures": {"2019": 5.1, "2018": 4.0, "2017": 3.9}, "Capital expenditures 20172019 -- Of which in Sweden": {"2019": 2.0, "2018": 1.3, "2017": 1.5}, "Capital expenditures 20172019 -- Share of annual sales": {"2019": 2.3, "2018": 1.9, "2017": 1.9}}
capital_expenditures_2019 = df["Capital expenditures 20172019 -- Capital expenditures"]["2019"]
capital_expenditures_2018 = df["Capital expenditures 20172019 -- Capital expenditures"]["2018"]
answer = capital_expenditures_2019 - capital_expenditures_2018