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% ( 4.0 % )
4.6% ( 4.6 % )
4.0% ( 4.0 % )
weighted average expected rate of return on plan assets
7.4% ( 7.4 % )
7.7% ( 7.7 % )
7.7% ( 7.7 % )
weighted average expected rate of compensation increase
3.5% ( 3.5 % )
3.9% ( 3.9 % )
3.8% ( 3.8 % )

.

Question: what was the decrease observed in the fair market value of plan assets of the benefit pension plans during 2014 and 2015?
Answer: 4.81%