A report from Quest Diagnostics, looking at workplace drug screenings, finds that of the over 6 million tests the company performed last year, 4.3% came back positive, compared to 3.9% in 2021. That’s the highest positive rate for the drug since 1997.

At the same time, amphetamine use was also on the rise, with usage climbing 15.4% over the 2021 numbers. Some 1.5% of the screenings tested positive in 2022 compared to 1.3% in 2021. (The data does not differentiate between prescription medicine and illegal drug use.)

“This historic rise seems to correspond with sharp increases in positivity for marijuana in both pre-employment and post-accident drug tests, suggesting that changing societal attitudes about marijuana may be impacting workplace behaviors and putting colleagues at risk,” said Keith Ward, general manager and vice president for employer solutions at Quest Diagnostics in a statement. “The increase in amphetamines positivity is also notable, given the addictive potential and health risks associated with this class of drugs.”

When tests took place after workplace accidents, the positivity rate of marijuana usage jumped to 7.3%, compared to 6.7% in 2021

The combined positive rate for all drugs stayed steady at 4.6%, once again tying the highest rate since 2001—and 30% above the record low, which took place from 2010-2012. Between 2012 and 2022, says Quest, post-accident marijuana positivity increased 204.2%.

The increase in the general U.S. workforce began the same year recreational marijuana was legalized in some states. Today, more than half the country’s population lives in states where marijuana is legal, whether recreationally or medicinally. Only 12 states still have laws completely banning its usage.