With the federal government set to legalize recreational cannabis use next year, a new study from the Centre for Addiction and Mental Health (CAMH) found that year cannabis use in Ontario has virtually doubled between 1996 and 2015 despite being illegal for those without a medical prescription.

A survey released yesterday said cannabis use by Ontario residents has risen from about eight per cent to nearly15 per cent. Significant increases were found among all age groups, but particularly among 18- to 29-year-olds millennials, with the proportion of cannabis users rising from about 18 per cent in 1996 to 38 per cent in 2015.

“We also see that the cannabis-using population is aging, as well,” said senior scientist Robert Mann, who co-authored the CAMH Monitor report on substance use and mental health status among a representative sample of more than 5,000 Ontario adults.

Last year, 23 per cent of those using cannabis were aged 50 and older — an eight-fold increase since the first study was made in 1977, when only three per cent of users were in that age bracket.

The CAMH Monitor is a collection of survey data that has been published every two years for almost the last four decades, allowing researchers to track long-term trends in the use of alcohol, drugs and tobacco.