the following table shows annual aircraft fuel consumption and costs , including taxes , for our mainline and regional operations for 2018 , 2017 and 2016 ( gallons and aircraft fuel expense in millions ) .
year gallons average price per gallon aircraft fuel expense percent of total operating expenses .

Year
Gallons
Average Priceper Gallon
Aircraft FuelExpense
Percent of TotalOperating Expenses
2018
4,447
$2.23
$9,896
23.6%
2017
4,352
1.73
7,510
19.6%
2016
4,347
1.42
6,180
17.6%

as of december 31 , 2018 , we did not have any fuel hedging contracts outstanding to hedge our fuel consumption .
as such , and assuming we do not enter into any future transactions to hedge our fuel consumption , we will continue to be fully exposed to fluctuations in fuel prices .
our current policy is not to enter into transactions to hedge our fuel consumption , although we review that policy from time to time based on market conditions and other factors .
fuel prices have fluctuated substantially over the past several years .
we cannot predict the future availability , price volatility or cost of aircraft fuel .
natural disasters ( including hurricanes or similar events in the u.s .
southeast and on the gulf coast where a significant portion of domestic refining capacity is located ) , political disruptions or wars involving oil-producing countries , economic sanctions imposed against oil-producing countries or specific industry participants , changes in fuel-related governmental policy , the strength of the u.s .
dollar against foreign currencies , changes in the cost to transport or store petroleum products , changes in access to petroleum product pipelines and terminals , speculation in the energy futures markets , changes in aircraft fuel production capacity , environmental concerns and other unpredictable events may result in fuel supply shortages , distribution challenges , additional fuel price volatility and cost increases in the future .
see part i , item 1a .
risk factors 2013 201cour business is very dependent on the price and availability of aircraft fuel .
continued periods of high volatility in fuel costs , increased fuel prices or significant disruptions in the supply of aircraft fuel could have a significant negative impact on our operating results and liquidity . 201d seasonality and other factors due to the greater demand for air travel during the summer months , revenues in the airline industry in the second and third quarters of the year tend to be greater than revenues in the first and fourth quarters of the year .
general economic conditions , fears of terrorism or war , fare initiatives , fluctuations in fuel prices , labor actions , weather , natural disasters , outbreaks of disease and other factors could impact this seasonal pattern .
therefore , our quarterly results of operations are not necessarily indicative of operating results for the entire year , and historical operating results in a quarterly or annual period are not necessarily indicative of future operating results .
domestic and global regulatory landscape general airlines are subject to extensive domestic and international regulatory requirements .
domestically , the dot and the federal aviation administration ( faa ) exercise significant regulatory authority over air carriers .
the dot , among other things , oversees domestic and international codeshare agreements , international route authorities , competition and consumer protection matters such as advertising , denied boarding compensation and baggage liability .
the antitrust division of the department of justice ( doj ) , along with the dot in certain instances , have jurisdiction over airline antitrust matters. .

Question: Analyse this data from a financial earnings document. what was the total aircraft fuel expense from 2016 to 2018 in millions
Choices:
4622.9
6181.3
23586.0
23586
16076.2
Correct choice index: 2