Hearts, kidneys and other donated organs have added more than 2 million years to the lives of the American patients who received them, according to a new analysis.

That tally, published this week by the journal JAMA Surgery, covers 25 years of organ donation in the U.S. Researchers started with 1987, the year when the United Network for Organ Sharing began keeping track of all organ transplants in the U.S.

Between Sept. 1, 1987, and Dec. 31, 2012, 533,329 patients received a donated organ (or perhaps two). Another 579,506 patients were put on the UNOS waiting list but didn’t get an organ. By comparing the outcomes for patients in both groups, the researchers were able to calculate how much longer the transplant recipients lived as a result of their new organs.

So far, that number adds up to 2,270,859 years — a “stellar accomplishment,” according to the study authors. And that number will keep getting bigger as long as any of the transplant recipients are still alive.