What is the total non-current portion of the deferred revenue between 2018 and 2019?
{"Deferred revenue: -- Products": {"December 31, 2019": 6593, "December 31, 2018": 5216}, "Deferred revenue: -- Services": {"December 31, 2019": 94571, "December 31, 2018": 92750}, "Deferred revenue: -- Total deferred revenue": {"December 31, 2019": 101164, "December 31, 2018": 97966}, "Deferred revenue: -- Less: current portion": {"December 31, 2019": -62233, "December 31, 2018": -63874}, "Deferred revenue: -- Non-current portion": {"December 31, 2019": 38931, "December 31, 2018": 34092}}
total_deferred_2019 = df["Deferred revenue: -- Total deferred revenue"]["December 31, 2019"]
total_deferred_2018 = df["Deferred revenue: -- Total deferred revenue"]["December 31, 2018"]
answer = total_deferred_2019 + total_deferred_2018