OTTAWA - More Canadian soldiers killed themselves in 2008 than the year before, but the military says the overall suicide rate has remained steady throughout the war in Afghanistan, despite the obvious stresses of the mission.

Fifteen active-duty members of the military took their own lives last year -- a rate of 23 per 100,000 -- versus 11 confirmed suicides in 2007, according to newly released Defence Department statistics.

But the average rate of suicide over three years, from 2005 to 2008, was 17.9 per 100,000. Those are the years which involved the heaviest combat in Afghanistan and the highest number of troop rotations.

Surprisingly, the military does not track suicides among reservists who are filling an ever-increasing number of the positions in the battle groups that are deployed for six month rotations in Kandahar.

The figures, from the military's medical branch, come amid greater public awareness of the issue following the apparent suicide of Maj. Michelle Mendes in Afghanistan and media coverage of the growing number of cases among U.S. soldiers.

There were 128 confirmed U.S. army suicides in 2008 -- a rate of 20.2 deaths per 100,000. The U.S. Marine Corp suicide rate was 19 per 100,000.

A broadcast report last year claimed the number of suicides in the Canadian Forces had doubled, but that information was based on data that was compiled from military police logs, which included other kinds of "sudden" deaths, such as accidents.

In considering the latest numbers, the Canadian military's top doctor zeroed in on the three-year average and said Canadians appeared to be faring better than their biggest ally when it comes to dealing with the stresses of war.

Commodore Hans Jung said there are some important differences that contribute to the slightly better rate, including the fact that Canadian troops deploy for six month tours. American units serve between nine and 15 months in war zones.

"That tour length is a huge issue," the military's surgeon-general said in an interview.

Since Canadians became involved in major combat in 2006, there have been regular debates within the upper ranks of the Defence Department about extending Canadian tour lengths for battle group soldiers, but the idea has always been vetoed. Troops who serve with support elements, such as the headquarters, are deployed for longer stretches.

Jung said the invoking of stop-loss orders on U.S. soldiers, which essentially prevent them from leaving the military even though their term is up, is another factor in the higher, average suicide rate there.

Canada's military also has a superior mental health-education and support system, Jung claimed.

Part of the reason is the size.

"They're so much larger and they deploy for such a long time; I think they have higher stresses," said Jung.

The death of Mendes, a 30-year-old rising star within the officer corps, brought the question of suicide prevention within the military into sharp focus.

Specific questions about screening and whether she should have been deployed for a second tour into one of the most senior intelligence positions in southern Afghanistan remain unanswered six months after her death.

The Canadian Forces National Investigative Service has not released the findings of its probe and claimed last month it was still awaiting autopsy results from the Ontario coroner -- a report that has apparently now been delivered.

What's troubling to some opposition members is the lack of attention paid to reservists who take their own lives.

Generally, suicides among part-time soldiers are brought to the attention of the military by civilian authorities, but a plan is underway to cross-reference the names of all military members since 1972 onward to Statistics Canada's mortality database.

Liberal MP Dan McTeague, who championed the plight of wounded soldiers and reservists, said absence of such data eight years after the war started is startling and speaks to how the contribution of citizen soldiers is downplayed.

"It's a glaring omission," he said. "One would think, considering the structure of the Armed Forces and how important reservists are to operations such as Afghanistan, that there would be particular paid to their situation.

"Anybody whose been close to this mission recognizes how indispensable these guys are."