pre_text: Adjusted EBITDA Non-GAAP Reconciliation (UNAUDITED) ($ in millions) (1) Refer to Non-GAAP Integration and Transformation Costs and Special Items table for details of the integration and transformation costs and special items included above.
table: Pro Forma (1)
table: 2019 2018 2017
table: Net income (loss) $(5,269) (1,733) 1,508
table: Income tax expense 503 170 (770)
table: Total other expense, net 2,040 2,133 2,147
table: Depreciation and amortization expense 4,829 5,120 5,125
table: Share-based compensation expenses 162 186 238
table: Goodwill impairment 6,506 2,726 0
table: Adjusted EBITDA 8,771 8,602 8,248
table: Exclude: transaction related expenses 0 0 192
table: Exclude: integration and transformation costs(1) 234 378 164
table: Exclude: special items(1) 65 60 82
table: Adjusted EBITDA excluding integration and transformation costs and special items $9,070 9,040 8,686
table: Total revenue $22,401 23,443 24,128
table: Adjusted EBITDA Margin 39.2% 36.7% 34.2%
table: Adjusted EBITDA Margin, excluding integration and transformation costs and special items 40.5% 38.6% 36.0%
question: Analyse this data from a financial earnings document. What is the average total revenue across the three years?