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:
| Year | Gallons | Average  Price per Gallon | Aircraft  Fuel Expense | Percent of Total Operating Expenses |
| --- | --- | --- | --- | --- |
| 2019 | 4,537 | $2.07 | $9,395 | 22.0% |
| 2018 | 4,447 | 2.23 | 9,896 | 23.6% |
Question:
What was American's annual aircraft fuel consumption in 2019?
Answer:
4,537