table of contents configuration , amenities provided to passengers , loyalty programs , the automation of travel agent reservation systems , onboard products , markets served and other services . we compete with both major network airlines and low-cost carriers throughout our network . international in addition to our extensive domestic service , we provide international service to canada , central and south america , asia , europe , australia and new zealand . in providing international air transportation , we compete with u.s . airlines , foreign investor-owned airlines and foreign state- owned or state-affiliated airlines , including carriers based in the middle east , the three largest of which we believe benefit from significant government subsidies . in order to increase our ability to compete for international air transportation service , which is subject to extensive government regulation , u.s . and foreign carriers have entered into marketing relationships , alliances , cooperation agreements and jbas to exchange traffic between each other 2019s flights and route networks . see 201cticket distribution and marketing agreements 201d above for further discussion . employees and labor relations the airline business is labor intensive . in 2016 , mainline and regional salaries , wages and benefits were our largest expense and represented approximately 35% ( 35 % ) of our total operating expenses . labor relations in the air transportation industry are regulated under the railway labor act ( rla ) , which vests in the national mediation board ( nmb ) certain functions with respect to disputes between airlines and labor unions relating to union representation and collective bargaining agreements ( cbas ) . when an rla cba becomes amendable , if either party to the agreement wishes to modify its terms , it must notify the other party in the manner prescribed under the rla and as agreed by the parties . under the rla , the parties must meet for direct negotiations , and , if no agreement is reached , either party may request the nmb to appoint a federal mediator . the rla prescribes no set timetable for the direct negotiation and mediation process . it is not unusual for those processes to last for many months and even for several years . if no agreement is reached in mediation , the nmb in its discretion may declare under the rla at some time that an impasse exists , and if an impasse is declared , the nmb proffers binding arbitration to the parties . either party may decline to submit to binding arbitration . if arbitration is rejected by either party , an initial 30-day 201ccooling off 201d period commences . following the conclusion of that 30-day 201ccooling off 201d period , if no agreement has been reached , 201cself-help 201d ( as described below ) can begin unless a presidential emergency board ( peb ) is established . a peb examines the parties 2019 positions and recommends a solution . the peb process lasts for 30 days and ( if no resolution is reached ) is followed by another 201ccooling off 201d period of 30 days . at the end of a 201ccooling off 201d period ( unless an agreement is reached , a peb is established or action is taken by congress ) , the labor organization may exercise 201cself-help , 201d such as a strike , and the airline may resort to its own 201cself-help , 201d including the imposition of any or all of its proposed amendments to the cba and the hiring of new employees to replace any striking workers . the table below presents our approximate number of active full-time equivalent employees as of december 31 , 2016 . mainline operations wholly-owned regional carriers total .
what portion of the total full-time employees of mainline operations are pilots and flight crew instructors?
.