What was the change in the benefit payments (non-discounted amounts) for maturity > 30 years?
{"Weighted average duration of the defined benefit obligation (years)": {"2019": 14.0, "2018": 15.0}, "Maturity analysis of benefit payments (non-discounted amounts) $ million -- Maturity  1 year": {"2019": 10.8, "2018": 10.4}, "Maturity analysis of benefit payments (non-discounted amounts) $ million -- Maturity > 1  5 years": {"2019": 45.6, "2018": 43.2}, "Maturity analysis of benefit payments (non-discounted amounts) $ million -- Maturity > 5  10 years": {"2019": 61.7, "2018": 119.0}, "Maturity analysis of benefit payments (non-discounted amounts) $ million -- Maturity > 10  20 years": {"2019": 114.3, "2018": 103.0}, "Maturity analysis of benefit payments (non-discounted amounts) $ million -- Maturity > 20  30 years": {"2019": 81.7, "2018": 68.0}, "Maturity analysis of benefit payments (non-discounted amounts) $ million -- Maturity > 30 years": {"2019": 63.0, "2018": 42.9}}
benefit_payments_2019 = df["Maturity analysis of benefit payments (non-discounted amounts) $ million -- Maturity > 30 years"]["2019"]
benefit_payments_2018 = df["Maturity analysis of benefit payments (non-discounted amounts) $ million -- Maturity > 30 years"]["2018"]
answer = benefit_payments_2019 - benefit_payments_2018