Table:
| (in thousands of $) | 2019 | 2018 | 2017 |
| --- | --- | --- | --- |
| Service cost | 162 | 250 | 313 |
| Interest cost | 1,740 | 1,687 | 1,901 |
| Expected return on plan assets | (375) | (926) | (843) |
| Recognized actuarial loss | 777 | 1,392 | 1,182 |
| Net periodic benefit cost | 2,304 | 2,403 | 2,553 |
Paragraphs:
22. PENSIONS
Defined contribution scheme
We operate a defined contribution scheme. The pension cost for the period represents contributions payable by us to the scheme. The charge to net income for the years ended December 31, 2019, 2018 and 2017 was $2.4 million, $1.9 million and $1.7 million, respectively.
Defined benefit schemes
We have two defined benefit pension plans both of which are closed to new entrants but still cover certain of our employees. Benefits are based on the employee's years of service and compensation. Net periodic pension plan costs are determined using the Projected Unit Credit Cost method. Our plans are funded by us in conformity with the funding requirements of the applicable government regulations. Plan assets consist of both fixed income and equity funds managed by professional fund managers. We have two defined benefit pension plans both of which are closed to new entrants but still cover certain of our employees. Benefits are based on the employee's years of service and compensation. Net periodic pension plan costs are determined using the Projected Unit Credit Cost method. Our plans are funded by us in conformity with the funding requirements of the applicable government regulations. Plan assets consist of both fixed income and equity funds managed by professional fund managers.
We use December 31 as a measurement date for our pension plans.
The components of net periodic benefit costs are as follows:
The components of net periodic benefit costs are recognized in the income statement within administrative expenses and vessel operating expenses.
The estimated net loss for the defined benefit pension plans that will be amortized from accumulated other comprehensive income into net periodic pension benefit cost during the year ended December 31, 2019 is $0.8 million (2018: $1.4 million).
Question:
How are net periodic pension plan costs determined?
Answer: Using the Projected Unit Credit Cost method