What was the change in non-current lease liabilities?
{"Maturity analysis - contractual undiscounted cash flow -- Less than one year": {"2019": 7.5, "2018": 5.2}, "Maturity analysis - contractual undiscounted cash flow -- One to five years": {"2019": 27.6, "2018": 25.6}, "Maturity analysis - contractual undiscounted cash flow -- More than five years": {"2019": 0.1, "2018": "-"}, "Maturity analysis - contractual undiscounted cash flow -- Total undiscounted lease liabilities as of 31 December": {"2019": 35.2, "2018": 30.8}, "Maturity analysis - contractual undiscounted cash flow -- Lease liabilities included under \"Borrowings\" as of 31 December": {"2019": 30.6, "2018": 25.3}, "Maturity analysis - contractual undiscounted cash flow -- Non-current": {"2019": 10.2, "2018": 3.2}, "Maturity analysis - contractual undiscounted cash flow -- Current": {"2019": 20.4, "2018": 22.1}}
non_current_liabilities_2019 = df["Maturity analysis - contractual undiscounted cash flow -- Non-current"]["2019"]
non_current_liabilities_2018 = df["Maturity analysis - contractual undiscounted cash flow -- Non-current"]["2018"]
answer = non_current_liabilities_2019 - non_current_liabilities_2018