Table:
0
A
B
C
D
1
($ in millions)
2
For the year ended December 31:
2019
2018
Yr.-to-Yr. Percent Change
3
Retirement-related plans—cost
4
Service cost
$385
$431
(10.7)%
5
Multi-employer plans
32
38
(16.9)
6
Cost of defined contribution plans
1,040
1,024
1.5
7
Total operating costs/ (income)
$1,457
$1,494
(2.5)%
8
Interest cost
$2,929
$2,726
7.4%
9
Expected return on plan assets
(4,192)
(4,049)
3.5
10
Recognized actuarial losses
1,819
2,941
(38.2)
11
Amortization of prior service costs/(credits)
(9)
(73)
(87.6)
12
Curtailments/settlements
41
11
262.2
13
Other costs
28
16
76.2
14
Total non-operating costs/(income)
$615
$1,572
(60.9)%
15
Total retirement-related plans—cost
$2,072
$3,066
(32.4)%

Questions and formulas:
Question: What was the increase / (decrease) in service cost from 2018 to 2019?
Formula: B4 - C4
Formula2: B4 - C4
Level: Calculation
Question: What was the average interest cost?
Formula: (B8 + C8) / 2
Formula2: (B8 + C8) / 2
Level: Calculation
Question: What was the increase / (decrease) in the Other costs from 2018 to 2019?
Formula: B13 - C13
Formula2: B13 - C13
Level: Calculation