While Long Island Rail Road workers feast on overtime, its service is the worst it’s been in nearly two decades, according to a state report released Thursday.

Nearly 21,400 LIRR trains were late, canceled or terminated mid-run in 2017, a 20 percent increase over 2016 and the poorest numbers in 18 years, State Comptroller Thomas DiNapoli’s office found.

Those delays and cancellations cost riders about $75 million in economic losses last year, says the report. Trains are considered late if they arrive at their final destination at least six minutes behind schedule.

“As millions of commuters can attest, the performance of the Long Island Rail Road has become unacceptable,” said DiNapoli.

MTA overtime numbers released earlier this month by The Empire Center show that the agency spent $1.2 billion on overtime last year — with most of the top 20 earners working for LIRR.

A squad of LIRR foremen raked in around $300,000 in overtime on top of their regular pay.

The MTA responded to the DiNapoli report by saying its leaders know there’s a problem and want to fix it.

LIRR President Patrick Nowakowski said last month he’s devising a performance-improvement plan. He plans to reveal the details next week.