Please read the following table in Markdown format and then answer the question according to the table. Table cells in one row are seperated by '|', and different rows are seperated by '
'.

Table:
|  | 2017 | 2016 (a) | 2015 | 2014 | 2013 |
| --- | --- | --- | --- | --- | --- |
| Direct to customer | 62% | 61% | 60% | 57% | 55% |
| Traditional agencies | 22% | 23% | 23% | 25% | 27% |
| Online travel agencies | 11% | 11% | 11% | 12% | 13% |
| Reservation call centers | 5% | 5% | 6% | 6% | 5% |
| Total | 100% | 100% | 100% | 100% | 100% |
Question:
What percentage of Alaska Air tickets were sold through brick-and-mortar travel agencies in 2015?
Answer:
23%