Read the following texts and table with financial data from an S&P 500 earnings report carefully.Based on the question-answer history (if provided), answer the last question. The answer may require mathematical calculation based on the data provided.


table of contents other areas in which we do business . depending on the scope of such regulation , certain of our facilities and operations , or the operations of our suppliers , may be subject to additional operating and other permit requirements , potentially resulting in increased operating costs . future regulatory developments future regulatory developments and actions could affect operations and increase operating costs for the airline industry , including our airline subsidiaries . see part i , item 1a . risk factors 2013 201cif we are unable to obtain and maintain adequate facilities and infrastructure throughout our system and , at some airports , adequate slots , we may be unable to operate our existing flight schedule and to expand or change our route network in the future , which may have a material adverse impact on our operations , 201d 201cour business is subject to extensive government regulation , which may result in increases in our costs , disruptions to our operations , limits on our operating flexibility , reductions in the demand for air travel , and competitive disadvantages 201d and 201cwe are subject to many forms of environmental regulation and may incur substantial costs as a result 201d for additional information . employees and labor relations the airline business is labor intensive . in 2015 , salaries , wages and benefits were our largest expenses and represented approximately 31% ( 31 % ) of our operating expenses . the table below presents our approximate number of active full-time equivalent employees as of december 31 , 2015 . mainline operations wholly-owned regional carriers total . <table class='wikitable'><tr><td>1</td><td>-</td><td>mainline operations</td><td>wholly-owned regional carriers</td><td>total</td></tr><tr><td>2</td><td>pilots and flight crew training instructors</td><td>13100</td><td>3200</td><td>16300</td></tr><tr><td>3</td><td>flight attendants</td><td>24100</td><td>1900</td><td>26000</td></tr><tr><td>4</td><td>maintenance personnel</td><td>14400</td><td>1800</td><td>16200</td></tr><tr><td>5</td><td>fleet service personnel</td><td>16100</td><td>3200</td><td>19300</td></tr><tr><td>6</td><td>passenger service personnel</td><td>16500</td><td>7100</td><td>23600</td></tr><tr><td>7</td><td>administrative and other</td><td>14700</td><td>2400</td><td>17100</td></tr><tr><td>8</td><td>total</td><td>98900</td><td>19600</td><td>118500</td></tr></table> .
Question: as of december 31, 2015, what percentage of the total of active full-time equivalent employees was due to flight attendants?

0.21941