U.S. airlines reduced the number of passengers involuntarily bumped from their seats on crowded planes to the lowest number on record in 2017, the U.S. Department of Transportation said on Thursday.

U.S. carriers bumped passengers at a rate of just 0.34 per 10,000 passengers last year, nearly halving the rate of 0.62 per 10,000 set in 2016.

Last year's rate was the lowest since record-keeping began in 1995, the Transportation Department said in a report.

The improvement follows an industry pledge to overhaul overbooking policies after the forceful removal of a passenger from an overbooked United Airlines flight last year sparked a worldwide backlash and calls for increased government oversight of airline regulations.

Delta Air Lines, the second largest U.S. carrier by passenger traffic, recorded the fewest bumped passengers in 2017, at a rate of 0.05 denied boarding per 10,000. United, the No. 3 U.S. carrier, bumped passengers at a rate of 0.23 per 10,000 passengers. American Airlines, the country's largest airline, had a rate of 0.38 per 10,000.

While a record-breaking year for airline safety and performance, 2017 was also a time of reckoning for carrier customer service practices, after a series of unflattering headlines and public relations nightmares shined a critical light on the industry.

After the United Airlines incident and a subsequent congressional inquiry into the matter, major U.S. carriers announced changes to their booking policies. These included increasing the maximum passenger incentive for passengers to forgo their flights, which rose to nearly $10,000 in the cases of United and Delta.

Southwest Airlines said the carrier would no longer overbook its flights. In 2017, Southwest bumped passengers at a rate of 0.53 per 10,000 passengers, ranking number nine out of 12 airlines measured.

Prior to the United incident, just one of the major U.S. carriers, JetBlue, had a policy explicitly stating it would not overbook its flights. In 2017, JetBlue bumped passengers at a rate of 0.41 out of 10,000 passengers.

In December, the number of customer complaints about U.S. carriers filed with the Transportation Department dropped to 628 from 1,254 in December 2016.