What is the percentage change in free cash flow in 2019?
{"Cash flows from operating activities": {"2019": 7958, "2018": 7384}, "Capital expenditures": {"2019": -3988, "2018": -3971}, "Cash dividends paid on preferred shares": {"2019": -147, "2018": -149}, "Cash dividends paid by subsidiaries to NCI": {"2019": -65, "2018": -16}, "Acquisition and other costs paid": {"2019": 60, "2018": 79}, "Voluntary DB pension plan contribution": {"2019": "\u2013", "2018": 240}, "Free cash flow": {"2019": 3818, "2018": 3567}}
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