The IdeaWorksCompany’s annual CarTrawler Reward Seat Availability Survey finds low-cost carriers Southwest and JetBlue offer U.S. travelers the lowest average reward seat pricing. The claim is based on an analysis of the average reward prices associated with domestic frequent-flyer programs that use ticket prices, rather than miles flown, as an accrual method.

JetBlue and Southwest were compared to American Airlines, Delta Air Lines and United Airlines, which all base accrual on fares paid. For low-fare economy passengers without elite tier status, the JetBlue TrueBlue and Southwest Rapid Rewards programs offer accrual at six points per dollar, compared to five miles per dollar at other airlines.

The reward prices per round-trip travel on Southwest and JetBlue average at 9,300 and 15,849 points, respectively. Meanwhile, Delta’s average reward prices per round-trip settle at 23,443 points, with American at a little more than 30,000 and United at nearly 34,000.

IdeaWorksCompany compared these findings to the same data from 2013, and found Southwest’s reward prices decreased over the last four years, by less than 1 percent, while JetBlue’s reward prices increased by the same, over the same time period. Delta impressively lowered reward prices by nearly 20 percent in the last four years. American lowered reward prices by 2 percent. United, however, raised reward prices by nearly 30 percent.