The rate of Canadians who report being sexually assaulted has held steady in recent years, even as the frequency of other crime has plummeted, according to a new Statistics Canada study that highlights the pervasiveness of a serious crime that seldom leads to prosecution.

Figures compiled from the agency's 2014 General Social Survey (GSS) on victimization show about 22 sexual assaults for every 1,000 Canadians aged 15 or older in 2014. That ratio has not budged since 2004, the last time the survey was administered.

Over that period, rates of other crimes measured by the survey – such as robbery and physical assault – dropped by upward of 35 per cent.

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"We are now accumulating a pretty incredible body of evidence on the prevalence of sexual assault and how we're failing to address it," said University of Ottawa criminology professor Holly Johnson, who once managed the survey during a 20-year career at Statscan. "We are not making any progress here."

More than 35,000 Canadians aged 15 or older responded to the GSS on victimization. Each answered a series of questions regarding sexual assault. The results form the basis for self-reported crime rates in the country and can conflict with police-reported crime rates. In 2014, for example, police recorded 20,735 victims of sexual assault while the GSS pegs the number of self-reported sexual assaults at 636,000.

The police-reported data exclude all incidents deemed unfounded by police, meaning investigators believe no crime occurred. The Globe and Mail has reported extensively on flaws in the way police categorize sex crimes as unfounded. On average, one out of every five sexual-assault reports is dismissed as unfounded, according to The Globe's examination of figures from major police agencies across the country.

Statistics Canada used to collect unfounded data, but ceased in 2006 due to "inconsistent reporting."

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After The Globe's investigation, the agency announced it would begin publishing the figures once again in close collaboration with the Canadian Association of Chiefs of Police.

The 2014 figures underscore a pressing conundrum for police forces. While the rate of self-reported sexual assault has flat-lined, the number of police-reported sexual assaults has declined by 20 per cent.

"To see that the same level of sexual assault is being perpetrated but fewer people are coming forward to police – that suggests we're really going backwards, doesn't it?" said Tracy Porteous, executive director of the Ending Violence Association of British Columbia. "I think the police have done an amazing job in targeting violent offenders. But if you disaggregate sexual violence and domestic violence, those two crimes are going up … We need to do something different."

The survey captured a range of explanations for why victims decided against reporting to police. Most common (71 per cent) was the perception that the crime was too inconsequential to report. In two-thirds of cases, the victim felt the assault was a private matter that should be handled informally.

But more than four out of every 10 respondents said they did not go to police owing to misgivings about the criminal-justice system: 40 per cent considered dealing with police too much of a hassle; 43 per cent felt police would dismiss their complaint as unimportant; and 40 per cent said punishment for their attacker would be inadequate.

Of all assaults that police deem founded, less than half result in a criminal charge, according to research by Dr. Johnson. Half of those charges result in prosecution. And half of those prosecutions result in a conviction. By the end of the judicial process, an estimated 0.3 per cent of all founded sexual-assault reports lead to a conviction.

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Women were the victims in 87 per cent of sexual assaults, according to the survey, which captured three types of sexual assault. One out of every five assaults involved a sexual attack. Another 71 per cent concerned unwanted sexual touching. In the remaining 9 per cent of cases, the victim could not consent for a range of reasons, including intoxication.

There is hope that the next GSS will record a more positive trend. Recent high-profile cases involving Jian Ghomeshi, Bill Cosby and Alberta judge Robin Camp have emphasized fixes that go beyond law enforcement. Dr. Johnson points to a new program called Man Up that encourages young men to take action against sexual violence as a constructive development.

"Most women don't want a justice-system solution," she said.

"They simply want to be treated with respect and not assaulted."