Table:
|  | 2019 | 2018 | $ CHANGE | % CHANGE |
| --- | --- | --- | --- | --- |
| Operating costs | (6,942) | (6,946) | 4 | 0.1% |
| Adjusted EBITDA | 5,414 | 5,321 | 93 | 1.7% |
| Adjusted EBITDA margin | 43.8% | 43.4% |  | 0.4 pts |
Paragraphs:
OPERATING COSTS AND ADJUSTED EBITDA
Bell Wireline operating costs were essentially stable year over year, decreasing by 0.1% in 2019, compared to 2018, resulting from: • The favourable impact from the adoption of IFRS 16 in 2019 • Continued effective cost containment • Lower pension expenses reflecting reduced DB costs
These factors were partly offset by: • Higher cost of goods sold related to the growth in product sales • Increased costs from the acquisition of Axia • Greater payments to other carriers from increased sales of international wholesale long distance minutes
Bell Wireline adjusted EBITDA grew by 1.7% in 2019, compared to last year, reflecting the growth in revenues as operating expenses were relatively stable year over year. Adjusted EBITDA margin increased to 43.8% in 2019, compared to the 43.4% achieved last year, resulting from the favourable impact of the adoption of IFRS 16 in 2019 and the flow-through of the service revenue growth, offset in part by higher low-margin product sales in our total revenue base.
Question:
What is the sum of the operating costs in 2018 and 2019?
Answer: -6942+-6946 = -13888