pre_text: 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.
table: 2019 2018 $ CHANGE % CHANGE
table: Operating costs (6,942) (6,946) 4 0.1%
table: Adjusted EBITDA 5,414 5,321 93 1.7%
table: Adjusted EBITDA margin 43.8% 43.4% 0.4 pts
question: Analyse this data from a financial earnings document. What is the sum of the operating costs in 2018 and 2019?