Contractual Obligations As of December 31, 2019, our contractual obligations were as follows:
(1) Interest on long-term debt includes amounts due on fixed and variable rate debt. As the rates on our variable debt are subject to change, the rates in effect at December 31, 2019 were used in determining our future interest obligations. Expected settlements of interest rate swap agreements were estimated using yield curves in effect at December 31, 2019.
(2) Unrecorded purchase obligations include binding commitments for future capital expenditures and service and maintenance agreements to support various computer hardware and software applications and certain equipment. If we terminate any of the contracts prior to their expiration date, we would be liable for minimum commitment payments as defined by the contractual terms of the contracts.
(3) Recorded obligations include amounts in accounts payable and accrued expenses for external goods and services received as of December 31, 2019 and expected to be settled in cash.
(4) Expected contributions to our pension and post-retirement benefit plans for the next 5 years. Actual contributions could differ from these estimates and extend beyond 5 years.
Defined Benefit Pension Plans As required, we contribute to qualified defined pension plans and non-qualified supplemental retirement plans (collectively the “Pension Plans”) and other post-retirement benefit plans, which provide retirement benefits to certain eligible employees. Contributions are intended to provide for benefits attributed to service to date. Our funding policy is to contribute annually an actuarially determined amount consistent with applicable federal income tax regulations.
The cost to maintain our Pension Plans and future funding requirements are affected by several factors including the expected return on investment of the assets held by the Pension Plans, changes in the discount rate used to calculate pension expense and the amortization of unrecognized gains and losses. Returns generated on the Pension Plans assets have historically funded a significant portion of the benefits paid under the Pension Plans. We used a weighted-average expected long-term rate of return of 6.97% and 7.03% in 2019 and 2018, respectively. As of January 1, 2020, we estimate the longterm rate of return of Plan assets will be 6.25%. The Pension Plans invest in marketable equity securities which are exposed to changes in the financial markets. If the financial markets experience a downturn and returns fall below our estimate, we could be required to make material contributions to the Pension Plans, which could adversely affect our cash flows from operations.
Net pension and post-retirement costs were $11.5 million, $5.6 million and $3.8 million for the years ended December 31, 2019, 2018 and 2017, respectively. We contributed $27.5 million, $26.2 million and $12.5 million in 2019, 2018 and 2017, respectively to our Pension Plans. For our other post-retirement plans, we contributed $8.5 million, $9.7 million and $6.5 million in 2019, 2018 and 2017, respectively. In 2020, we expect to make contributions totaling approximately $25.0 million to our Pension Plans and $8.9 million to our other post-retirement benefit plans. Our contribution amounts meet the minimum funding requirements as set forth in employee benefit and tax laws. See Note 11 to the consolidated financial statements for a more detailed discussion regarding our pension and other post-retirement plans.
Table:
(In thousands) | Less than 1 Year | 1 -3 Years | 3 -5 Years | Thereafter | Total
Long-term debt | $ 18,350 | $ 521,700 | $ 1,729,663 | $ — | $ 2,269,713
Interest on long-term debt obligations (1) | 128,731 | 246,834 | 65,552 | — | 441,117
Finance leases | 10,280 | 8,285 | 3,404 | 6,604 | 28,573
Operating leases | 7,860 | 10,751 | 5,660 | 10,691 | 34,962
Unconditional purchase obligations: |  |  |  |  | 
Unrecorded (2) | 36,488 | 37,830 | 19,954 | 1,371 | 95,643
Recorded (3) | 98,035 | — | — | — | 98,035
Pension funding (4) | 33,861 | 64,311 | 65,959 | — | 164,131


Question: What was the change in pension funding between 1-3 years and 3-5 years?
Answer: 1648
Calculation: 65,959 - 64,311