2014 2013 2012 U.S. Non-U.S. U.S. Non-U.S. U.S. Non-U.S. Pension benefit obligations: Discount rate 3.81% 3.75% 4.63% 4.15% 3.77% 3.93% Net periodic benefit cost: Discount rate 4.63% 4.15% 3.77% 3.93% 4.57% 4.98% Rate of compensation increase N/A 3.77% N/A 3.73% N/A 3.14% Expected return on plan assets 7.00% 3.41% 7.00% 3.35% 7.00% 3.74% The pension plan discount rate assumptions are evaluated annually in consultation with our outside actuarial advisers.  Long-term interest rates on high quality corporate debt instruments are used to determine the discount rate. For our lar gest  plans, discount rates are developed using a discounted bond portfolio analysis, with appropriate consideration given to defined  benefit payment terms and duration of the liabilities. The expected rate of return on plan assets was selected on the basis of our long-term view of return and risk assumptions  for major asset classes. We define long-term as forecasts that span at least the next  ten years. Our long-term outlook is  influenced by a combination of return expectations by individual asset class, actual historical experience and our diversified  investment strategy. We consult with and consider the opinions of financial professionals in developing appropriate capital  market assumptions. Return projections are also validated using a simulation model that incorporates yield curves, credit  spreads and risk premiums to project long-term prospective returns.  The appropriateness of the expected rate of return is  assessed on an annual basis and revised if necessary . We have a high percentage of total assets in fixed income securities since  the benefit accruals are frozen for all of our U.S. pension plans. Based on this assessment, we have selected a  7.00% expected  return on asset assumption for 2015 for our U.S. plans, the same rate we used for 2014. The significant weighted-average assumptions used in the measurement of OPEB obligations at December 31 of each year  and the net periodic benefit cost for each year are as follows: The discount rate selection process was similar to the process used for the pension plans.  Assumed health care cost trend  rates have a significant ef fect on the health care obligation. To determine the trend rates, consideration is given to the plan  design, recent experience and health care economics. A one-percentage-point change in assumed health care cost trend rates would have the following ef fects for 2014: Estimated future benefit payments and contributions  — Expected benefit payments by our pension and OPEB plans for each of  the next five years and for the period 2020 through 2024 are as follows: 68 1% Point Increase 1% Point Decrease Effect on total of service and interest cost components $ 1 $ (1) Effect on OPEB obligations 14 (12) 2014 2013 2012 Non-U.S. Non-U.S. Non-U.S. OPEB benefit obligations: Discount rate 3.84% 4.65% 3.90% Net periodic benefit cost: Discount rate 4.65% 3.90% 4.18% Initial health care costs trend rate 5.91% 6.11% 6.40% Ultimate health care costs trend rate 5.02% 5.03% 5.02% Year ultimate reached 2018 2018 2018