Seattle City Light 2016 ANNUAL REPORT | Audited Financial Statements 44 THE CITY OF SEATTLE—CITY LIGHT DEPARTMENT NOTES TO FINANCIAL STATEMENTS AS OF AND FOR THE YEARS ENDED DECEMBER 31, 2016 AND 2015 - 44 - or demographic factors in the measurement of total pension liability, which are amortized to pension expense over a period equal to the expected remaining service life of employees receiving pension benefits. See Note 12 Seattle City Employees’ Retirement System. The excess of costs incurred over the carrying value of bonds refunded on early extinguishment of debt are reported as Deferred outflows of resources and amortized as a component of interest expense using the effective interest method over the terms of the issues to which they pertain. See Note 9 Long-term Debt. Deferred outflows of resources at December 31, 2016 and 2015 consisted of the following: ($ in millions) 2016 2015 Deferred outflows of resources: Unrealized contributions and losses related to pension 64.6 $ 33.4 $ Charges on advance refunding 30.3 16.4 Total 94.9 $ 49.8 $ 9. LONG-TERM DEBT At December 31, 2016 and 2015, the Department’s long-term debt consisted of the following prior lien or parity bonds: LONG-TERM ($ in millions) Fixed Rate Maturity Year Original Issuance 2016 2015 Prior Lien Bonds: 2016A ML&P Revenue Bonds 4.050% fixed 2041 31.9 $ 31.9 $ - $ 2016B ML&P Refunding Revenue Bonds 4.000%–5.000% 2029 116.9 115.3 - 2016C ML&P Improvement and Refunding Revenue Bonds 4.000%–5.000% 2046 160.8 160.8 - 2015A ML&P Revenue Bonds 4.000%–5.000% 2045 171.9 167.5 171.9 2015B1 ML&P Adjustable Rate Revenue Bonds variable rates 2045 50.0 50.0 50.0 2015B2 ML&P Adjustable Rate Revenue Bonds variable rates 2045 50.0 50.0 50.0 2014 ML&P Improvement and Refunding Revenue Bonds 4.000%–5.000% 2044 265.2 239.5 250.0 2013 ML&P Improvement and Refunding Revenue Bonds 2.000%–5.000% 2043 190.8 181.9 184.8 2012A ML&P Improvement and Refunding Revenue Bonds 2.000%–5.000% 2041 293.3 261.1 272.5 2012C ML&P Clean Renewable Energy Bonds 3.400%–3.750% 2033 43.0 43.0 43.0 2011A ML&P Improvement and Refunding Revenue Bonds 1.000%–5.500% 2036 296.3 239.8 253.0 2011B ML&P Clean Renewable Energy Bonds 5.750%–5.750% 2027 10.0 10.0 10.0 2010A ML&P Build America Bonds 4.447%–5.570% 2040 181.6 181.6 181.6 2010B ML&P Improvement and Refunding Revenue Bonds 2.000%–5.000% 2026 596.9 340.9 421.2 2010C ML&P Recovery Zone Economic Development Bonds 5.590%–5.590% 2040 13.3 13.3 13.3 2008 ML&P Revenue and Refunding Revenue Bonds 4.000%–6.000% 2029 257.4 31.5 169.5 Total prior lien bonds 2,729.3 $ 2,118.1 $ 2,070.8 $