What was the percentage change in liquidity in 2019 from 2018?
{"Cash and cash equivalents, including restricted cash": {"2019": 72.5, "2018": 127.4, "2017": 134.2}, "Undrawn credit facilities": {"2019": 173.1, "2018": 278.7, "2017": 270.7}, "Liquidity": {"2019": 245.6, "2018": 406.1, "2017": 404.9}}
liquidity_2019 = df["Liquidity"]["2019"]
liquidity_2018 = df["Liquidity"]["2018"]
answer = ( liquidity_2019 - liquidity_2018 ) / liquidity_2018 * 100.0