Table:
revised average level
previously published average level
average revision

millions of dollars

average 2013 to 2015

compensation of employees
994,953
994,994
-41

gross operating surplus
527,815
521,574
6,241

gross mixed income
222,867
223,650
-783

taxes less subsidies on production
83,913
83,160
753

taxes less subsidies on products and imports
125,358
125,991
-633

gdp at market prices
1,955,614
1,949,508
6,106

2013

compensation of employees
961,179
962,100
-921

gross operating surplus
518,267
511,461
6,806

gross mixed income
216,355
216,480
-125

taxes less subsidies on production
81,301
80,656
645

taxes less subsidies on products and imports
120,319
120,019
300

gdp at market prices
1,897,531
1,892,193
5,338

2014

compensation of employees
997,998
998,586
-588

gross operating surplus
553,497
543,051
10,446

gross mixed income
221,340
222,245
-905

taxes less subsidies on production
84,358
83,422
936

taxes less subsidies on products and imports
125,003
126,127
-1,124

gdp at market prices
1,983,117
1,973,043
10,074

2015

compensation of employees
1,025,682
1,024,296
1,386

gross operating surplus
511,680
510,210
1,470

gross mixed income
230,907
232,224
-1,317

taxes less subsidies on production
86,079
85,403
676

taxes less subsidies on products and imports
130,752
131,826
-1,074

gdp at market prices
1,986,193
1,983,288
2,905

Statement: gross operating surplus was adjusted upward by $6.8 billion for 2013.
Question: what was the amount that gross operating surplus was adjusted upward by for 2013?
Answer: [6806.0]