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 Ended December 31, | Year Ended December 31, | Increase (Decrease) | % Increase (Decrease) |
| --- | --- | --- | --- | --- |
|  | 2016 | 2015 |  |  |
| Salaries and related costs | $10,034 | $8,776 | $1,258 | 14.3 % |
| Aircraft fuel and related taxes | 5,133 | 6,544 | (1,411) | (21.6)% |
| Regional carriers expense | 4,311 | 4,241 | 70 | 1.7 % |
| Contracted services | 1,991 | 1,848 | 143 | 7.7 % |
| Depreciation and amortization | 1,902 | 1,835 | 67 | 3.7 % |
| Aircraft maintenance materials and outside repairs | 1,823 | 1,848 | (25) | (1.4)% |
| Passenger commissions and other selling expenses | 1,710 | 1,672 | 38 | 2.3 % |
| Landing fees and other rents | 1,490 | 1,493 | (3) | (0.2)% |
| Profit sharing | 1,115 | 1,490 | (375) | (25.2)% |
| Passenger service | 907 | 872 | 35 | 4.0 % |
| Aircraft rent | 285 | 250 | 35 | 14.0 % |
| Other | 1,986 | 2,033 | (47) | (2.3)% |
| Total operating expense | $32,687 | $32,902 | $(215) | (0.7)% |
Question:
how much was the operating expense for regional carriers in 2016?
Answer:
4,311