Despite heated debate and a contentious vote in the House of Commons over the Conservative government's decision to extend the anti-ISIS bombing mission into Syria last March, Canada's six CF-18s in the Middle East have conducted a tiny fraction of their airstrikes in that embattled country.

Canada has carried out just four airstrikes in Syria, according to an analysis of reports posted on the Department of National Defence's website. Those four airstrikes represent just two per cent of all airstrikes Canada has conducted in the region, the other 98 per cent having taken place in Iraq.

In stark contrast, the U.S.-led coalition overall has conducted 29 per cent of its airstrikes in Syria and 71 per cent in Iraq since Canada first dropped bombs on Syria in early April.

About three-quarters of Canada's airstrikes have occurred in Iraq north of Baghdad, primarily in the region around Mosul and between that major city and Sinjar, near the Syrian border, largely in support of Kurdish troops. The rest of the attacks have occurred west of Baghdad, principally around Ramadi, which Iraqi forces are currently trying to wrest from ISIS control.

Since flying its first missions for the coalition on Oct. 30, 2014, Canada's six CF-18 Hornets have flown 1,280 sorties as of Jan. 9, 2016, representing five per cent of all sorties flown by coalition fighter aircraft over that time. The CC-150T Polaris aerial refueller has flown two per cent of all sorties flown by the coalition's refuelling aircraft, while the two CP-140 Aurora reconnaissance aircraft have flown 3.5 per cent of all reconnaissance missions the coalition has undertaken.

But less than a fifth of sorties flown by the CF-18s resulted in a strike against ISIS targets. Through to Jan. 5, 2016, Canada conducted 226 airstrikes in both Iraq and Syria.

That represents 2.6 per cent of all the coalition's airstrikes since Canada's involvement began, suggesting that a higher proportion of sorties flown by Canada's allies have included an attack against an ISIS target than those flown by the CF-18s.

A spokeswoman for the Canadian Armed Forces said many factors determine the frequency of airstrikes, including the availability of targets.

"Coalition aircraft are assigned on a daily basis to a specific target or a target area where ISIL is known to operate. In a dynamic setting, the target may or may not appear during an assigned mission," Maj. Isabelle Bresse wrote in an email to CBC News.

ISIS 'fighting positions' targeted

An analysis of the daily reports released by the government shows that a significant majority of airstrikes conducted by Canada's CF-18s have been against what the Defence Department calls "ISIS fighting positions." In all, about 70 per cent of strikes have been against these kinds of targets — and all of them have been in Iraq, where Canada has allies on the ground as well as Canadian soldiers spotting targets.

Canadian airstrikes in the Middle East, by target, since the mission began in 2014 (based on daily Defence Department reports).

So-called "strong points," staging areas and ISIS compounds, represented 11 per cent of Canada's targets, while another six per cent were ISIS vehicles and four per cent were ISIS storage facilities or factories, based on the daily reports from the Defence Department.

The department also provided numbers to CBC News related to the number of targets struck by Canadian Forces broken into three broader categories:

242 against ISIS fighting positions.

81 against ISIS equipment and vehicles.

22 against ISIS improvised explosive device factories and storage facilities.

According to Bresse, "every target is selected and identified in co-ordination with coalition partners with the ultimate goal of degrading ISIS capabilities. Every target engaged is part of a network of [ISIS] military capabilities. Any part of that network affects [ISIS's] ability to conduct local activities on any single day."

Up to the end of 2015, the Defence Department said, Canada's CF-18s "deployed 546 precision-guided munitions on [ISIS] targets."

Steady pace of activity

The pace of coalition airstrikes has held relatively steady since an increase last spring, according to a CBC analysis of the coalition's daily reports of activity in the region compiled by the website Airwars.

With the exception of a spike in airstrikes in January 2015, Canada's participation in the mission was growing steadily through to July 2015, when airstrikes peaked at 30 in a single month. The airstrikes then diminished in August and September, dropping to their lowest level since February. That followed a broader pattern, with coalition airstrikes as a whole peaking in July before decreasing over the summer.

The numbers suggest, then, that the reduction in Canada's participation in August and September was part of a coalition-wide decrease in operations, and not related to the federal election campaign.

The coalition decrease was primarily driven by fewer airstrikes in Syria, whereas airstrikes in Iraq have held steady since July. The drop in Syria coincided with the start of Russia's involvement in that country.

Coalition activity increased in November, with more attacks in Syria. But the numbers suggest the Nov. 13 Paris attacks were not necessarily the catalyst for this increase in activity. In the two weeks prior to those attacks, the coalition was averaging 14 airstrikes per day in the Middle East. Since the Paris attacks, they have averaged 12 airstrikes per day.

Canada's participation also increased month-over-month from that September low. But Canada's share of the load, which peaked at three per cent or more between May and July 2015, was lower over the last six months of 2015 than it had been in the first six months of the year.

In the first week of 2016, to Friday, however, Canada participated in just over five per cent of the coalition's airstrikes, its highest rate of participation since the mission began. Whether or not this increase in activity will hold remains to be seen, as Canada's experience in the Middle East has often seen intense periods of activity followed by long periods of calm.

The longest period of calm may come soon, as the Liberals have promised to pull Canada's fighter jets out of the Middle East this year. While this withdrawal may have an impact on operations in Iraq, it seems the impact will be negligible on the coalition's bombing campaign in Syria.