What was the percentage change in free cash flow in 2019 from 2018?
{"Cash flow": {"2019": "\u00a3m", "2018": "\u00a3m"}, "Adjusted operating profit": {"2019": 282.7, "2018": 264.9}, "Depreciation and amortisation (excluding IFRS 16)": {"2019": 34.3, "2018": 32.9}, "Depreciation of leased assets": {"2019": 11.3, "2018": "\u2013"}, "Cash payments to pension schemes more than the charge to adjusted operating profit": {"2019": -5.2, "2018": -4.6}, "Equity settled share plans": {"2019": 6.2, "2018": 5.7}, "Working capital changes": {"2019": -21.4, "2018": -22.5}, "Repayments of principal under lease liabilities": {"2019": -11.2, "2018": "\u2013"}, "Capital additions (including software and development)": {"2019": -62.4, "2018": -43.4}, "Capital disposals": {"2019": 3.8, "2018": 9.9}, "Adjusted cash from operations": {"2019": 238.1, "2018": 242.9}, "Net interest": {"2019": -5.4, "2018": -6.7}, "Income taxes paid": {"2019": -78.4, "2018": -61.6}, "Free cash flow": {"2019": 154.3, "2018": 174.6}, "Net dividends paid": {"2019": -76.3, "2018": -67.3}, "Purchase of employee benefit trust shares/Proceeds from issue of shares": {"2019": -12.5, "2018": -5.0}, "(Acquisitions)/Disposals of subsidiaries (including costs)": {"2019": -138.5, "2018": 48.8}, "Cash flow for the year": {"2019": -73.0, "2018": 151.1}, "Exchange movements": {"2019": 13.6, "2018": -13.3}, "Opening net debt": {"2019": -235.8, "2018": -373.6}, "Net debt at 31st December (excluding IFRS 16)": {"2019": -295.2, "2018": -235.8}, "IFRS 16 lease liability": {"2019": -38.9, "2018": "\u2013"}, "Net debt and lease liability at 31st December": {"2019": -334.1, "2018": -235.8}}
free_cash_flow_2019 = df["Free cash flow"]["2019"]
free_cash_flow_2018 = df["Free cash flow"]["2018"]
answer = ( free_cash_flow_2019 - free_cash_flow_2018 ) / free_cash_flow_2018 * 100.0