pre_text: The following table summarizes the components of net periodic pension cost recognized in the consolidated statements of operations for the plans for the years ended December 31, 2019, 2018 and 2017: The components of net periodic pension cost other than the service cost component are included in other, net within other income (expense) in the consolidated statements of operations. In 2019, we purchased a group annuity contract to transfer the pension benefit obligations and annuity administration for a select group of retirees or their beneficiaries to an annuity provider. Upon issuance of the group annuity contract, the pension benefit obligation of $24.4 million for approximately 500 participants was irrevocably transferred to the annuity provider. The purchase of the group annuity was funded directly by the assets of the Pension Plans. During the year ended December 31, 2019, we recognized a pension settlement charge of $6.7 million as a result of the transfer of the pension liability to the annuity provider and other lump sum payments made during the year. In 2018 and 2017, the Retirement Plan was amended to freeze benefit accruals under the cash balance benefit plan for certain participants under collective bargaining agreements. As a result of these amendments, we recognized a pre-tax curtailment gain of $1.2 million and $1.3 million as a component of net periodic pension cost during the years ended December 31, 2018 and 2017, respectively.
table: (In thousands) 2019 2018 2017
table: Service cost $ 50 $ 5,809 $ 3,055
table: Interest cost 30,327 28,870 21,882
table: Expected return on plan assets (34,627) (38,640) (28,459)
table: Amortization of:
table: Net actuarial loss 2,890 6,110 6,244
table: Prior service cost (credit) 123 (204) (316)
table: Plan curtailment — (1,156) (1,337)
table: Plan settlement 6,726 94 17
table: Net periodic pension cost $ 5,489 $ 883 $ 1,086
question: Analyse this data from a financial earnings document. What was the average net actuarial loss for 2017-2019?