user
Instruction
Answer the question based on the provided table.


Table
Table Title: revisions to income-based gross domestic product components
Table Content:
<table border="1" cellspacing="0">
<tr> <td rowspan="2">  </td> <td> revised average level </td> <td> previously published average level </td> <td> average revision </td> </tr>
<tr> <td colspan="3"> millions of dollars </td> </tr>
<tr> <td> average 2013 to 2015 </td> <td colspan="3">  </td> </tr>
<tr> <td> compensation of employees </td> <td> 994,953 </td> <td> 994,994 </td> <td> -41 </td> </tr>
<tr> <td> gross operating surplus </td> <td> 527,815 </td> <td> 521,574 </td> <td> 6,241 </td> </tr>
<tr> <td> gross mixed income </td> <td> 222,867 </td> <td> 223,650 </td> <td> -783 </td> </tr>
<tr> <td> taxes less subsidies on production </td> <td> 83,913 </td> <td> 83,160 </td> <td> 753 </td> </tr>
<tr> <td> taxes less subsidies on products and imports </td> <td> 125,358 </td> <td> 125,991 </td> <td> -633 </td> </tr>
<tr> <td> gdp at market prices </td> <td> 1,955,614 </td> <td> 1,949,508 </td> <td> 6,106 </td> </tr>
<tr> <td> 2013 </td> <td colspan="3">  </td> </tr>
<tr> <td> compensation of employees </td> <td> 961,179 </td> <td> 962,100 </td> <td> -921 </td> </tr>
<tr> <td> gross operating surplus </td> <td> 518,267 </td> <td> 511,461 </td> <td> 6,806 </td> </tr>
<tr> <td> gross mixed income </td> <td> 216,355 </td> <td> 216,480 </td> <td> -125 </td> </tr>
<tr> <td> taxes less subsidies on production </td> <td> 81,301 </td> <td> 80,656 </td> <td> 645 </td> </tr>
<tr> <td> taxes less subsidies on products and imports </td> <td> 120,319 </td> <td> 120,019 </td> <td> 300 </td> </tr>
<tr> <td> gdp at market prices </td> <td> 1,897,531 </td> <td> 1,892,193 </td> <td> 5,338 </td> </tr>
<tr> <td> 2014 </td> <td colspan="3">  </td> </tr>
<tr> <td> compensation of employees </td> <td> 997,998 </td> <td> 998,586 </td> <td> -588 </td> </tr>
<tr> <td> gross operating surplus </td> <td> 553,497 </td> <td> 543,051 </td> <td> 10,446 </td> </tr>
<tr> <td> gross mixed income </td> <td> 221,340 </td> <td> 222,245 </td> <td> -905 </td> </tr>
<tr> <td> taxes less subsidies on production </td> <td> 84,358 </td> <td> 83,422 </td> <td> 936 </td> </tr>
<tr> <td> taxes less subsidies on products and imports </td> <td> 125,003 </td> <td> 126,127 </td> <td> -1,124 </td> </tr>
<tr> <td> gdp at market prices </td> <td> 1,983,117 </td> <td> 1,973,043 </td> <td> 10,074 </td> </tr>
<tr> <td> 2015 </td> <td colspan="3">  </td> </tr>
<tr> <td> compensation of employees </td> <td> 1,025,682 </td> <td> 1,024,296 </td> <td> 1,386 </td> </tr>
<tr> <td> gross operating surplus </td> <td> 511,680 </td> <td> 510,210 </td> <td> 1,470 </td> </tr>
<tr> <td> gross mixed income </td> <td> 230,907 </td> <td> 232,224 </td> <td> -1,317 </td> </tr>
<tr> <td> taxes less subsidies on production </td> <td> 86,079 </td> <td> 85,403 </td> <td> 676 </td> </tr>
<tr> <td> taxes less subsidies on products and imports </td> <td> 130,752 </td> <td> 131,826 </td> <td> -1,074 </td> </tr>
<tr> <td> gdp at market prices </td> <td> 1,986,193 </td> <td> 1,983,288 </td> <td> 2,905 </td> </tr>
</table>


Question
what was the amount the estimates of employee compensation were revised downward for 2013?


Answer Format
The final answer should be concise and use the following format:
```json
{
    "answer": [
        "answer1",
        "answer2",
        ...
    ]
}
```
rule
["921"]