Seattle City Light 2016 ANNUAL REPORT | Audited Financial Statements 56 THE CITY OF SEATTLE—CITY LIGHT DEPARTMENT NOTES TO FINANCIAL STATEMENTS AS OF AND FOR THE YEARS ENDED DECEMBER 31, 2016 AND 2015 - 56 - 2016 2015 Total Pension Liability Service cost 24.5 $ 23.1 $ Interest on total pension liability 62.3 59.3 Effect of plan changes Effect of economic/demographic gains or losses 0.5 - Effect of assumptions changes or inputs - - ` (39.0) (36.9) Refund of contributions (3.9) (3.7) Net change in total pension liability 44.4 41.8 Total pension liability, beginning of period 841.5 799.7 Effect of change in proportionate share (2.4) - Adjusted total pension liability, beginning of period 839.1 799.7 Total pension liability, end of period 883.5 841.5 Plan fiduciary net position Benefit payments (39.0) (36.9) Refunds of contributions (3.9) (3.7) Administrative expenses (2.0) (1.3) Member contributions 16.1 15.7 Employer contributions 24.7 22.1 Net investment income 1.7 30.0 Net change in Plan fiduciary net position (2.4) 25.9 Plan fiduciary net position, beginning of period 569.7 543.8 Effect of change in proportionate share (1.6) - Adjusted fiduciary net position, beginning of period 568.1 543.8 Plan fiduciary net position, end of period 565.7 569.7 Net pension liability, end of period 317.8 $ 271.8 $ Changes in Net Pension Liability (In millions) Fiscal Year Ended December 31 The Department recognized pension expense of $40.8 million and $29.5 million for the years ended December 31, 2016, and 2015, respectively. Actuarial assumptions –The total pension liability at December 31, 2016 and 2015, was based on actuarial valuations as of December 31, 2015 and 2014, respectively, using the following actuarial methods and assumptions:   Actuarial Cost Method Individual Entry Age Normal Amortization Method Level percent or level dollar Level percent Closed, open, or layered periods Closed Amortization Period and Start Date 30 years as of January 1, 2013 Valuation Amortization Growth Rate 4.00% Asset Valuation Method Smoothing period 5 years