OTTAWA -- The number of police-reported cannabis-offences declined for the fifth straight year, Statistics Canada said Monday, a downward trend that began long before the Liberals brought forward their plan to legalize the drug for recreational use.

The annual tally of police-reported crime from the Canadian Centre for Justice Statistics said there were about 55,000 offences related to marijuana reported to police in 2016, about 6,000 fewer than reported the year before -- despite previous data showing consumption of the drug on the rise.

The Liberal government has introduced legislation to legalize marijuana -- a goal it intends to achieve by next summer -- but has decided against decriminalizing simple possession in the interim, which the NDP has been urging them to do.

Statistics Canada said police charged 17,733 people with possession of pot last year.

That is a drop of about 3,600 from 2015, but still accounts for 76 per cent of all cannabis-related charges.

"We've still got a significant number of people being charged for simple possession of cannabis in this country," said Eugene Oscapella, a lawyer who lectures on drug policy in the criminology department at the University of Ottawa.

Statistics Canada also said the combined rate of drug-related offences for substances other than cannabis and cocaine, which had also been on the decline, has been increasing since 2010.

That included a seven-per-cent increase in the number of police-reported offences related to the possession of drugs such as prescription drugs, including opioids such as fentanyl, LSD and so-called "date rape" drugs in 2016, compared to the previous year.

There was also a slight uptick in the number of drug-impaired driving violations -- 3,098 in 2016 compared to 2,755 the year before.

Still, 96 per cent of all police-reported impaired driving incidents involved alcohol last year, with only four per cent involving drugs.

Statistics Canada suggested one reason the rate is so low is that impairment from drugs is difficult to measure.

Oscapella said the legalization of marijuana should come with more public awareness of its true effects on driving.

"Before, all we said was 'Thou shall not use.' We paid very little attention to educating people about social responsibility and driving," he said.

Meanwhile, the national crime rate did not change in 2016.

The national crime rate has been on a downward trend since the early 1990s, although there were increases reported in both 2003 and 2015.

Statistics Canada said there were nearly 1.9 million Criminal Code incidents -- excluding traffic offences -- reported by police in 2016, about 27,700 more than in 2015.

However, the severity of the crimes increased slightly for the second year in a row.

The agency said the one-per-cent increase in its crime severity index in 2016 was largely driven by a continued increase in the rate of police-reported fraud, which was up by 14 per cent over the previous year.

That includes identity fraud, which was up by 16 per cent, and identity theft, which was up by 21 per cent.

Rebecca Kong, chief of the policing services program at Statistics Canada, said some specific scams, such as those involving fraudsters purporting to be from the Canada Revenue Agency, could have led to the higher number of fraud crimes reported to police.

"It could be also just an increase in awareness among victims and an increase in encouraging of reporting also," she said.

Irvin Waller, a criminology professor at the University of Ottawa, said little is known about the true rate of victimization from fraud in Canada, but data from the United Kingdom shows that about 80 per cent of these sorts of crimes go unreported.

He urged Statistics Canada to include a question about fraud on its next national survey on victimization.

"I think this small uptick is a reason to want to know more about what's behind it," said Waller.

There were also reported increases in the rate of some violent crimes.

Among them was a 30-per-cent increase in the rate of police-reported incidents of sexual violations against children, which Statistics Canada said could be partly due to recently introduced harsher penalties changing the way these types of crimes are classified for the annual report.

Statistics Canada also said the rate of police-reported sexual assaults was 15-per-cent lower than a decade earlier, despite the self-reported sexual assault rate remaining unchanged over roughly the same period.

"This demonstrates that, due to a range of factors, police-reported data can underestimate the nature and extent of sexual assault," the agency said in its release Monday.

Police reported 611 homicides in 2016, which is two more than the previous year, but because the size of the population grew, the rate actually decreased by one per cent to 1.68 homicides per 100,000 people.

The city with the highest homicide rate was Thunder Bay, Ont., followed by Edmonton and Regina.