WASHINGTON — The Pentagon's top 100 contractors raked in $175.1 billion in obligated contracts in 2015, down slightly from 2014's total of $177.6 billion, according to government figures released this week.

Lockheed Martin was the largest single contractor for the US government in 2015, easily lapping the rest of the field with $36.2 billion. The next closest competitor was Boeing at $16.6 billion.The federal government’s top 100 as a whole obligated $238.5 billion in 2015, meaning the DoD represented about 73.5 percent of those contracts awarded to the biggest firms.

General Dynamics ($13.6 billion), Raytheon ($13.1 billion) and Northrop Grumman ($10.6 billion) rounded out the top five contractors. Health care services firm McKesson, which has a series of major contracts with the Tricare system, was the only non-defense contractor to make it into the top eight overall federal contractors.

The vendor with the most contracts awarded by the Pentagon was FedEx, with 6.1 million, or roughly 46 percent of all contracts handed out by the department. The next closest by number of actions was Cardinal Health, which accounted for just over 2.3 percent of total transactions.

But the number that matters is dollars, and by that regard, Lockheed Marin continues to reign. The world's largest defense firm, which also topped the contracting list in 2013 and 2014, ensures its dominance of the department with a mix of high-end, exquisite systems and cheaper more numerous weapons and sensors, said Byron Callan, an industry analyst with Capital Alpha Partners.

"Lockheed Martin's dominance can be explained by the F-35, Trident Fleet Ballistic Missile, C-130J and electronics, weapons and services programs too numerous to list," Callan said. "Their dominance should increase with next year's data as it should reflect the Sikorsky acquisition, though the divestiture of ISGS should somewhat offset the contribution from helicopters."

Lockheed was the top contractor for the Navy ($15.5 billion), Air Force ($7.3 billion) and Army ($4 billion), as well as for US Special Operations Command ($656.4 million).

Twitter: @AaronMehta