Delta Air Lines distributed $1.6 billion in profit-sharing to its 90,000 employees on Friday, a record for any U.S. company.

The distribution has become a Valentine’s Day ritual for Delta in recent years, representing an income boost that, except in the finance industry, is rare to most workers in America. It has also become a moment when unions draw attention to the inequalities in the airline industry, which relies, for some services, heavily on subcontractors that don’t pay their workers nearly as well.

This year’s payout at Delta works out to nearly $17,800 per employee and represented a 16% bonus to average worker pay, the airline said.

The pay averages are skewed by the high pay that pilots receive, reaching well above $200,000 for the most senior pilots. As a result, most Delta workers receive bonuses that are smaller than the average. All of Delta’s full-time, part-time and “ready reserve” employees qualify for the profit-sharing pool except for its officers and directors, who are paid with incentives based on other measures.

Its latest profit-sharing payout represents a sharp jump from the $1.3 billion it distributed last year and beat the previous record payout of $1.5 billion in 2016.

Delta has generally produced strong profits since the last economic downturn in 2008 and 2009. It became one of the industry’s best performers after consolidation, relatively low fuel prices, and improvements to fleets and routes all combined to end decades of volatility in the airline business.

Delta is third in passenger traffic at Philadelphia International Airport, according to the airport.

“Profit-sharing is one of the most important days of the year,” Joanne Smith, the company’s personnel chief, said in a statement. “It’s all about Delta people sharing in the success they make possible through hard work and a focus on our customers.”

Delta tweaked its profit-sharing model in recent years to give nonunion workers the same payout structure as its unionized pilots.

Last week, a union attempting to organize Delta’s flight attendants, the Association of Flight Attendants, used the buildup to the company’s profit-sharing distribution to promote itself at flight bases. In a statement, the AFA said it wanted Delta’s flight attendants to know that profit-sharing has become a standard practice in the airline industry because unions at other airlines negotiated for it. The AFA distributed candy hearts that said “Like it? Lock it in” to help get the message across.

Separately, the union Unite Here staged protests Friday afternoon at catering services at 16 U.S. airports, including four Delta bases, to seek higher pay and benefits for workers who prepare meals for flights.

Unite Here represents about 450 workers at LSG Sky Chefs kitchen at Minneapolis-St. Paul International Airport, which serves Delta flights. The union said its recent survey showed huge variances in health coverage at the MSP catering service, with 47% of workers lacking any form of health insurance.

Delta also uses the profit-sharing day to promote other corporate initiatives, this year a plan to spend $1 billion over the next decade to mitigate polluting emissions from its aircraft and ground vehicles. While the airline has purchased carbon-offset credits in the past, Delta’s new spending will focus on clean-air technology, other innovations and waste reduction.

“Carbon offsets are not the solution,” chief executive Ed Bastian said on CNBC. “We need to be investing in projects that make a difference.”

The airline also rolled out a plane that had been repainted with the words “Thank You” in giant red letters and a dedication on the nose of the plane to the “world’s best employees & customers.” Inside the giant red letters, the names of all 90,000 Delta employees were printed in smaller dark-red letters.

Delta at last year’s profit-sharing announcement said employees could add to their vacation benefits a paid day off to volunteer at a nonprofit organization of their choice.