91 Pension expense included the following components (in millions): U.S. Plans Y ear ended Non-U.S. Plans Y ear ended   Dec 31, 2012 Dec 31, 2011 Dec 31, 2010 Dec 31, 2012 Dec 31, 2011 Dec 31, 2010 Pension expense:             Service cost $ 1.8 $ 1.4 $ 1.4 $ 4.3 $ 3.1 $ 2.7 Interest cost 7.7 8.1 8.3 6.1 5.7 5.6 Expected return on plan assets (9.1 ) (10.6 ) (9.2 ) (2.0 ) (2.4 ) (2.0 ) Amortization of prior service cost 0.1 0.1 0.1 1.4 0.3 0.2 Amortization of net loss 8.3 5.1 4.8 1.2 1.2 0.5 Amortization of transition obligation — — — 0.2 0.2 0.2 Curtailment (gain) loss — — — — — (1.8 ) Settlement (gain) loss — — — 0.1 0.3 0.3 Net pension expense $ 8.8 $ 4.1 $ 5.4 $ 11.3 $ 8.4 $ 5.7 The estimated net loss for the defined benefit pension plans that will be amortized from accumulated other comprehensive income into net pension expense over the next fiscal year is $ 1 1.4 million . The prior service cost to be amortized from accumulated other comprehensive income into net pension expense over the next fiscal year is immaterial. General Cable evaluates its actuarial assumptions at least annually , and adjusts them as necessary . The Company uses a measurement date of December 31 for all of its defined benefit pension plans. The weighted average assumptions used in determining benefit obligations were:   U.S. Plans Non-U.S. Plans   Dec 31, 2012 Dec 31, 2011 Dec 31, 2012 Dec 31, 2011 Discount rate 4.10 % 4.70 % 4.20 % 5.20 % Expected rate of increase in future compensation levels 2.00 % 2.00 % 4.10 % 4.40 % The weighted average assumptions used to determine net pension expense were:   U.S. Plans Non-U.S. Plans   Dec 31, 2012 Dec 31, 2011 Dec 31, 2010 Dec 31, 2012 Dec 31, 2011 Dec 31, 2010 Discount rate 4.70 % 5.40 % 6.00 % 5.10 % 5.60 % 6.20 % Expected rate of increase in future compensation levels 2.00 % 2.00 % 2.00 % 6.10 % 4.30 % 5.50 % Long-term expected rate of return on plan assets 7.50 % 8.50 % 8.50 % 4.50 % 7.20 % 6.90 % Pension expense for the defined benefit pension plans sponsored by General Cable is determined based principally upon certain actuarial assumptions, including the discount rate and the expected long-term rate of return on assets. The discount rates for the U.S. defined benefit pension plans were determined based on a review of long-term bonds that receive one of the two highest ratings given by a recognized rating agency which are expected to be available during the period to maturity of the projected pension benefit obligations and based on information received from actuaries. Non-U.S. defined benefit pension plans followed a similar evaluation process based on financial markets in those countries where General Cable provides a defined benefit pension plan. The weighted-average long-term expected rate of return on assets is based on input from actuaries, including their review of historical 10-year , 20-year , and 25-year rates of inflation and real rates of return on various broad equity and bond indices in conjunction with the diversification of the asset portfolio. The Company’ s overall investment strategy is to diversify its investments for the qualified U.S. defined benefit pension plan based on an asset allocation assumption of 65% allocated to equity investments, with an expected real rate of return of 8% , and 35% to fixed-income investments, with an expected real rate of return of 2% , and an assumed long-term rate of inflation of 3% . Equity investments primarily include investments in lar ge-cap and mid-cap companies primarily located in the United States. The actual asset allocations were 66% of equity investments and 34% of fixed-income investments at December 31, 2012 and 66% of equity investments and 34% of fixed-income investments at December 31, 201 1 . T able of Contents