One-time employee bonuses in collective bargaining agreements are on the decline as the summer progresses, according to the latest biweekly update of Bloomberg Law’s union wage data report.

With one-time payments taken into account, union employees received an average 3.5% wage increase in the first year of collective bargaining agreements so far this year. That’s down from 3.6% two weeks ago and from a high of 3.9% in late January.

Without bonuses, the average increase remained unchanged since the last biweekly update at 3.2%. That means bonuses have been a drag on the overall figures.

Lump-sum factored wage increases spiked...