< PrevNext > 73. Omnicom Group New York Share 2019 U.S.-Booked Air Volume: $52 millionU.S.-originating air volume for marketing communications business Omnicom Group fell from a BTN-estimated $61 million in 2018 to an estimated $52 million in 2019. Employee numbers decreased fractionally from 70,400 to 70,000, a third consecutive year of decline. Reported revenue was down 2.2 percent to $4.9 billion, while salary and service costs, which include business travel, fell 3 percent. Omnicom's most recent environmental report states that greenhouse gas emissions caused by the group's business travel declined by 9 percent in 2018.