Cannabis is more popular among college students that at any time since the mid-1980s, according to a new study from the University of Michigan.

The university polls more than 1,000 people aged 19-22 across America each year for its Monitoring the Future Panel study. This year the study found that 43% of college students reported using marijuana in the previous 12 months, while 25% said they had used it in the past 30 days.

That is a significant increase upon last year’s survey, which revealed that 38% of students had used cannabis in the past year and 21% in the past month.

Use of marijuana among full-time students aged 19-22 is now at the highest level since 1983.

The researchers also polled high school graduates aged 19-22 that do not attend college full-time. Among that group, it found that 43% had used cannabis in the past year and 27% in the past month. These are also the highest levels seen since the 1980s.

The number of students that reported vaping cannabis in the past month also increased from 5.2% in 2017 to 10.9% in 2018.

“This doubling in vaping marijuana among college students is one of the greatest one-year proportional increases we have seen among the multitude of substances we measure since the study began over 40 years ago,” said John Schulenberg, principal investigator of the Monitoring the Future Panel Study.

The researchers suggested that the perceived risk of harm from regular marijuana use has decreased significantly over the years and now stands at its lowest level since the survey began in 1980. Many different states across the country have legalized marijuana for recreational or medicinal purposes, or both, while it is fully legal in Canada.

Perceptions of risk peaked in 1991, when marijuana use was at historic lows, but people are now much more likely to use it on a regular basis.

More than one in 10 Americans aged 19-22 who do not attend college reported smoking cannabis daily or almost every day, compared to 5.8% of college students.

The survey use found that alcohol use continues to decline among this age group and the amount that smoke cigarettes is down to a record low.