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unconditional purchase obligations approximately $390 of our long-term unconditional purchase obligations relate to feedstock supply for numerous hyco (hydrogen, carbon monoxide, and syngas) facilities. the price of feedstock supply is principally related to the price of natural gas. however, long-term take-or-pay sales contracts to hyco customers are generally matched to the term of the feedstock supply obligations and provide recovery of price increases in the feedstock supply. due to the matching of most long-term feedstock supply obligations to customer sales contracts, we do not believe these purchase obligations would have a material effect on our financial condition or results of operations. refer to note 17, commitments and contingencies, to the consolidated financial statements for additional information on our unconditional purchase obligations. the unconditional purchase obligations also include other product supply and purchase commitments and electric power and natural gas supply purchase obligations, which are primarily pass-through contracts with our customers. in addition, purchase commitments to spend approximately $540 for additional plant and equipment are included in the unconditional purchase obligations in 2016. we also purchase materials, energy, capital equipment, supplies, and services as part of the ordinary course of business under arrangements that are not unconditional purchase obligations. the majority of such purchases are for raw materials and energy, which are obtained under requirements-type contracts at market prices. obligation for future contribution to an equity affiliate on 19 april 2015, a joint venture between air products and acwa holding entered into a 20-year oxygen and nitrogen supply agreement to supply saudi aramco 2019s oil refinery and power plant being built in jazan, saudi arabia. air products owns 25% (25%) of the joint venture and guarantees the repayment of its share of an equity bridge loan. in total, we expect to invest approximately $100 in this joint venture. as of 30 september 2015, we recorded a noncurrent liability of $67.5 for our obligation to make future equity contributions based on advances received by the joint venture under the loan. income tax liabilities noncurrent deferred income tax liabilities as of 30 september 2015 were $903.3. tax liabilities related to unrecognized tax benefits as of 30 september 2015 were $97.5. these tax liabilities were excluded from the contractual obligations table, as it is impractical to determine a cash impact by year given that payments will vary according to changes in tax laws, tax rates, and our operating results. in addition, there are uncertainties in timing of the effective settlement of our uncertain tax positions with respective taxing authorities. refer to note 23, income taxes, to the consolidated financial statements for additional information. pension benefits the company sponsors defined benefit pension plans and defined contribution plans that cover a substantial portion of its worldwide employees. the principal defined benefit pension plans 2014the u.s. salaried pension plan and the u.k. pension plan 2014were closed to new participants in 2005 and were replaced with defined contribution plans. over the long run, the shift to defined contribution plans is expected to reduce volatility of both plan expense and contributions. the fair market value of plan assets for our defined benefit pension plans as of the 30 september 2015 measurement date decreased to $3916.4 from $4114.6 at the end of fiscal year 2014. the projected benefit obligation for these plans was $4787.8 and $4738.6 at the end of the fiscal years 2015 and 2014, respectively. refer to note 16, retirement benefits, to the consolidated financial statements for comprehensive and detailed disclosures on our postretirement benefits. pension expense.
|  | 2015 | 2014 | 2013 |
| --------- | --------- | --------- | --------- |
| Pension expense | $135.6 | $135.9 | $169.7 |
| Special terminations, settlements, and curtailments (included above) | 35.2 | 5.8 | 19.8 |
| Weighted average discount rate | 4.0% | 4.6% | 4.0% |
| Weighted average expected rate of return on plan assets | 7.4% | 7.7% | 7.7% |
| Weighted average expected rate of compensation increase | 3.5% | 3.9% | 3.8% |
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Please answer the following questions with expressions if necessary.
what was the fair market value of plan assets of the benefit pension plans in 2015?
assistant
3916.4
human
and what was it in 2014?
assistant
4114.6
human
what was, then, the change over the year?
assistant
subtract(3916.4, 4114.6)
human
what was the fair market value of plan assets of the benefit pension plans in 2014?
assistant
4114.6
human
and how much does that change represent in relation to this 2014 fair market value?
assistant
subtract(3916.4, 4114.6), divide(#0, 4114.6)