Nearly five million Canadians spent money on marijuana last year, spending an average of about $1,200 each, according to new federal data.

That's one of the main takeaways of a Statistics Canada report released Thursday that attempts to quantify the size of the market leading up to legalization this summer.

The data agency warns that because so much of the current market operates outside the lines of legality, some of the findings in the report are based on "a number of assumptions, models and sparse data sources related to the production of the mostly illegal cannabis industry," Statistics Canada says.

The data agency estimates Canadian adults spent $5.7 billion on marijuana last year — 90 per cent of it for illegal, non-medical purposes.

The almost $6-billion figure compares with the just over $22 billion that Canadians spent on alcohol last year, and the $16 billion they spent on tobacco products.

In terms of production, however, the marijuana industry is now bigger than Canada's beer or tobacco industries. The country produced:

About $3.4 billion worth of cannabis in 2014.

About $2.9 billion in the brewing industry.

$1 billion in tobacco products.

That's mainly because the brewing and tobacco industries are heavily dependent on imports, unlike cannabis, most of which is produced and consumed in Canada.

The data agency estimates Canadians only imported about $300 million worth of illegal marijuana last year. In the 1960s, more than 40 per cent of the pot consumed in Canada came from elsewhere.

"A substantial amount of the tobacco and alcohol consumed in Canada is imported, which contributes to the smaller size of these industries compared with cannabis," the report said.

Canada also exported $1.2 billion worth of illegal cannabis last year, Statistics Canada said.

Statistics Canada also back-dated its data to 1961 and calculated that the price of marijuana has, on average, increased by about 3.3 per cent per year. Inflation-adjusted, the price for a gram of cannabis peaked at $12 in 1989, and has declined by an average of 1.7 per cent per year since then, because of oversupply.

By last year, the price of a gram had fallen to $7.50 a gram, the report estimates.