34. Retirement Benefits (continued) (b) Changes in the present value of the defined benefit obligations are as follows: 2022 2021 HK$M HK$M At 1st January 1,442 1,361 Current service cost 114 101 Interest expense 30 22 Actuarial (gains)/losses from changes in: – financial assumptions (436) 147 Experience losses/(gains) 18 (40) Transfer 5 (25) Benefits paid (155) (124) At 31st December 1,018 1,442 The weighted average duration of the defined benefit obligations is 10.92 years (2021: 10.90 years). (c) Changes in the fair value of plan assets are as follows: 2022 2021 HK$M HK$M At 1st January 1,255 1,226 Interest income 27 20 Return on plan assets, excluding interest income (173) 82 Contributions by employers 73 76 Transfer 5 (25) Benefits paid (155) (124) At 31st December 1,032 1,255 There were no plan amendments, curtailments or settlements during the year. (d) Net expenses recognised in the consolidated statement of profit or loss are as follows: 2022 2021 HK$M HK$M Current service cost 114 101 Net interest cost 3 2 117 103 The above net expenses were included in cost of sales and administrative expenses in the consolidated statement of profit or loss. Total retirement benefit costs charged to the consolidated statement of profit or loss for the year ended 31st December 2022 amounted to HK$132 million (2021: HK$124 million), including HK$15 million (2021: HK$21 million) in respect of defined contribution schemes. The actual return on defined benefit plan assets was a loss of HK$146 million (2021: gain of HK$102 million). SWIRE PROPERTIES ANNUAL REPORT 2022 185