What is the percentage change in the contract liabilities from 2018 to 2019?
{"": {"Year Ended December 31,": 2019, "": 2018}, "Contract assets": {"Year Ended December 31,": 218, "": 210}, "Contract liabilities": {"Year Ended December 31,": 346, "": 359}}
contract_liabilities_2019 = df["Contract liabilities"]["Year Ended December 31,"]
contract_liabilities_2018 = df["Contract liabilities"][""]
answer = ( contract_liabilities_2019 - contract_liabilities_2018 ) / contract_liabilities_2018 * 100.0