What was the percentage change in deferred revenue in 2019 from 2018?
{"": {"2019": "", "2018": "(in millions)"}, "Accrued payroll and employee benefits": {"2019": 455, "2018": 565}, "Dividends payable to shareholders": {"2019": 308, "2018": 303}, "Restructuring reserves": {"2019": 245, "2018": 141}, "Income taxes payable": {"2019": 94, "2018": 109}, "Deferred revenue": {"2019": 36, "2018": 27}, "Interest payable": {"2019": 31, "2018": 34}, "Share repurchase program payable": {"2019": 18, "2018": 94}, "Other": {"2019": 426, "2018": 438}, "Accrued and other current liabilities": {"2019": 1613, "2018": 1711}}
deferred_revenue_2019 = df["Deferred revenue"]["2019"]
deferred_revenue_2018 = df["Deferred revenue"]["2018"]
answer = ( deferred_revenue_2019 - deferred_revenue_2018 ) / deferred_revenue_2018 * 100.0