F-22  For 2013, 2012 and 2011, the discount rate was based on a Citigroup yield curve of high quality corporate bonds with cash  flows matching our plans' expected benefit payments. The expected return on plan assets is based on our asset allocation mix  The weighted average assumptions used to determine benefit obligations for the pension benefit plans and other benefit plans  at December 31, 2013, 2012 and 2011 are as follows:  The weighted average assumptions used to determine net periodic benefit cost in the accounting for the pension benefit  plans and other benefit plans for the years ended December 31, 2013, 2012 and 2011 are as follows:  Additional Information The 2014 estimated amortization of amounts in other accumulated comprehensive income are as follows:  The Company's funding policy for U.S. plans generally is to contribute annually into trust funds at a rate that provides for  future plan benefits and maintains appropriate funded percentages. Annual contributions to the U.S. qualified plans are at  least sufficient to satisfy regulatory funding standards and are not more than the maximum amount deductible for income tax  purposes. The funding policies for the international plans conform to local governmental and tax requirements. The plans'  assets are invested primarily in stocks and bonds.  Unrecognized prior service cost is amortized over the average remaining service period of each active employee.  Changes in the Plan assets and benefit obligations recognized in other comprehensive income:  MINERALS TECHNOLOGIES INC. AND SUBSIDIARY COMPANIES  NOTES TO CONSOLIDATED FINANCIAL STATEMENTS  Pension Benefits  Post-retirement Benefits  Millions of Dollars  2013  2012  2013  2012  Current year actuarial gain (loss)................................. $  26.1 $  (17.6 )  $  0.7  $ 2.7  Amortization of actuarial (gain) loss ........................... 8.8  8.4  -- (0.1)  Amortization of prior service credit (gain) loss ........... 0.6  0.7  (1.9)  (1.8)  Total recognized in other comprehensive income ....... $  35.5 $  (8.5)  $  (1.2)  $ 0.8  The components of net periodic benefit costs are as follows:  Pension Benefits  Post-retirement Benefits  Millions of Dollars  2013 2012  2011  2013  2012  2011 Service cost ............................................ $  8.4   $  8.1  $  7.1  $  0.6  $ 0.6 $ 0.7  Interest cost ............................................ 11.3  11.6 11.6  0.3  0.4 0.6  Expected return on plan assets ............... (14.8)  (13.5 )  (13.8 )  --  -- --  Amortization of prior service cost.......... 1.0  1.2  1.3  (3.1)  (3.1)  (3.1)  Recognized net actuarial (gain) loss ....... 13.9  13.3  8.6  -- (0.1)  0.1  Settlement /curtailment loss ................... --  0.2  0.5  --  --  --  Net periodic benefit cost ........................ $  19.8   $  20.9 $  15.3  $  (2.2)  $ (2.2)   $  (1.7)  Millions of Dollars Pension  Benefits  Post- Retirement  Benefits  Amortization of prior service credit (gain) loss  $  1.0  $  (3.1)  Amortization of net (gain) loss  7.2  (0.1)  Total costs to be recognized  $  8.2  $  (3.2)  2013  2012  2011  Discount rate.................................................. 3.80% 4.32% 5.70%  Expected return on plan assets....................... 7.18% 7.06% 7.25%  Rate of compensation increase ...................... 3.16% 3.11% 3.20%  2013  2012  2011  Discount rate.................................................. 4.37% 3.77% 4.30%  Rate of compensation increase ...................... 3.10% 3.14% 3.10% 