Table:
|  | 2019 | 2018 | 2017(1) |
| --- | --- | --- | --- |
| Gross Debt | $35,039 | 36,352 | 38,053 |
| Cash and cash equivalents | (1,690) | (488) | (551) |
| Net debt | $33,349 | 35,864 | 37,502 |
| Adjusted EBITDA excluding integration and transformation costs and special items (1) | $9,070 | 9,040 | 8,686 |
| Net Debt to Adjusted EBITDA Ratio | 3.7 | 4.0 | 4.3 |
Paragraphs:
Net Debt to Adjusted EBITDA Ratio
(UNAUDITED)
($ in millions)
(1) 2017 Adjusted EBITDA shown pro forma, assuming the Level 3 acquisition and the colocation and data center sale took place on January 1, 2017.
Question:
Which years does the table show the Net Debt to Adjusted EBITDA Ratio?
Answer: 2019, 2018, 2017