is included on page FS-54 in Note 22 under the relevant headings. Actual rates may vary significantly from estimates because of unanticipated changes in the world's financial markets.

For 2014, the company used an expected long-term rate of return of 7.5 percent and a discount rate of 4.3 percent for U.S. pension plans. For the 10 years ending December 31, 2014, actual asset returns averaged 6.0 percent for the plan. The actual return for 2014 was more than 7.5 percent. Additionally, with the exception of two years within this 10-year period, actual asset returns for this plan equaled or exceeded 7.5 percent during each year.

Total pension expense for 2014 was $1.2 billion. An increase in the expected long-term return on plan assets or the discount rate would reduce pension plan expense, and vice versa. As an indication of the sensitivity of pension expense to the long-term rate of return assumption, a 1 percent increase in this assumption for the company’s primary U.S. pension plan, which accounted for about 39 percent of companywide pension expense, would have reduced total pension plan expense for 2014 by approximately $98 million. A 1 percent increase in the discount rate for this same plan would have reduced pension expense for 2014 by approximately $229 million.

The aggregate funded status recognized at December 31, 2014, was a net liability of approximately $4.7 billion. An increase in the discount rate would decrease the pension obligation, thus changing the funded status of a plan. At December 31, 2014, the company used a discount rate of 3.7 percent to measure the obligations for the U.S. pension plans. As an indication of the sensitivity of pension liabilities to the discount rate assumption, a 0.25 percent increase in the discount rate applied to the company’s primary U.S. pension plan, which accounted for about 63 percent of the companywide pension obligation, would have reduced the plan obligation by approximately $403 million, which would have decreased the plan’s underfunded status from approximately $1.6 billion to $1.2 billion.

For the company’s OPEB plans, expense for 2014 was $219 million, and the total liability, which reflected the unfunded status of the plans at the end of 2014, was $3.7 billion. For the main U.S. OPEB plan, the company used a 4.7 percent discount rate to measure expense in 2014, and a 4.1 percent discount rate to measure the benefit obligations at December 31, 2014. Discount rate changes, similar to those used in the pension sensitivity analysis, resulted in an immaterial impact on 2014 OPEB expense and OPEB liabilities at the end of 2014. For information on the sensitivity of the health care cost-trend rate, refer to FS-54 in Note 22 under the heading “Other Benefit Assumptions.”

Differences between the various assumptions used to determine expense and the funded status of each plan and actual experience are included in actuarial gain/loss. Refer to page FS-53 in Note 22 for a description of the method used to amortize the $7.2 billion of before-tax actuarial losses recorded by the company as of December 31, 2014, and an estimate of the costs to be recognized in expense during 2015. In addition,