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, | Year Ended December 31, | Year Ended December 31, | Year Ended December 31, |
| --- | --- | --- | --- | --- | --- | --- |
|  |  | 2017 | 2016 | 2015 | 2014 | 2013 |
| Passengers (thousands) (a) |  | 108,017 | 101,007 | 96,327 | 91,475 | 91,329 |
| Revenue passenger miles (“RPMs”) (millions) (b) |  | 193,444 | 186,181 | 183,642 | 179,015 | 178,578 |
| Available seat miles (“ASMs”) (millions) (c) |  | 234,576 | 224,692 | 219,989 | 214,105 | 213,007 |
| Cargo ton miles (millions) |  | 3,316 | 2,805 | 2,614 | 2,487 | 2,213 |
| Passenger load factor (d) |  | 82.5% | 82.9% | 83.5% | 83.6% | 83.8% |
| Passenger revenue per available seat mile (“PRASM”) (cents) |  | 11.32 | 11.31 | 11.97 | 12.51 | 12.20 |
| Total revenue per available seat mile (cents) |  | 13.51 | 13.50 | 14.19 | 14.81 | 14.51 |
| Average yield per revenue passenger mile (“Yield”) (cents) (e) |  | 13.73 | 13.65 | 14.34 | 14.96 | 14.56 |
| Cost per available seat mile (“CASM”) (cents) |  | 12.59 | 12.22 | 12.42 | 14.03 | 14.31 |
| Average price per gallon of fuel, including fuel taxes |  | $        1.72 | $        1.49 | $        1.96 | $        2.98 | $        3.12 |
| Fuel gallons consumed (millions) |  | 3,357 | 3,261 | 3,216 | 3,183 | 3,204 |
| Average stage length (miles) (f) |  | 1,806 | 1,859 | 1,922 | 1,958 | 1,934 |
| Average daily utilization of each aircraft (hours) (g) |  | 10:27 | 10:06 | 10:24 | 10:26 | 10:28 |
| Consolidated | Passengers (thousands) (a) | 148,067 | 143,177 | 140,369 | 138,029 | 139,209 |
| Consolidated | RPMs (millions) (b) | 216,261 | 210,309 | 208,611 | 205,559 | 205,167 |
| Consolidated | ASMs (millions) (c) | 262,386 | 253,590 | 250,003 | 246,021 | 245,354 |
| Consolidated | Passenger load factor (d) | 82.4% | 82.9% | 83.4% | 83.6% | 83.6% |
| Consolidated | PRASM (cents) | 12.35 | 12.40 | 13.11 | 13.72 | 13.50 |
| Consolidated | Total revenue per available seat mile (cents) | 14.38 | 14.42 | 15.15 | 15.81 | 15.60 |
| Consolidated | Yield (cents) (e) | 14.98 | 14.96 | 15.72 | 16.42 | 16.14 |
| Consolidated | CASM (cents) | 13.05 | 12.70 | 13.08 | 14.85 | 15.09 |
| Consolidated | Average price per gallon of fuel, including fuel taxes | $1.74 | $1.49 | $1.94 | $2.99 | $3.13 |
| Consolidated | Fuel gallons consumed (millions) | 3,978 | 3,904 | 3,886 | 3,905 | 3,947 |
| Consolidated | Average stage length (miles) (f) | 1,460 | 1,473 | 1,487 | 1,480 | 1,445 |
Question:
How much gallon of fuel has been consumed for the mainline of United Airlines in 2016?
Answer:
3,261