What is the change in non-current accrued benefit liability between 2018 and 2019?
{"": {"2019": "(Amounts in thousands)", "2018": ""}, "Current accrued benefit liability": {"2019": 335, "2018": 340}, "Non-current accrued benefit liability": {"2019": 6904, "2018": 6168}, "Total accrued benefit liability": {"2019": 7239, "2018": 6508}}
noncurrent_accrued_benefit_liability_2019 = df["Non-current accrued benefit liability"]["2019"]
noncurrent_accrued_benefit_liability_2018 = df["Non-current accrued benefit liability"]["2018"]
answer = noncurrent_accrued_benefit_liability_2019 - noncurrent_accrued_benefit_liability_2018