OTTAWA (Reuters) - The Canadian population grew by 5.9 percent over five years to 33.5 million people in 2011, the fastest growth rate in the Group of Eight leading industrialized nations, the country’s five-year census revealed on Wednesday.

Statistics Canada, which conducted the census, said net immigration accounted for two-thirds of the population growth rate in the past decade. This contrasts with the United States, whose recent growth has been mainly the result of natural increase, the difference between births and deaths.

The Canadian population grew from 31.6 million in 2006 and is now almost double what it was in 1961, when Canada was experiencing a baby boom.

Each of the 10 provinces had more people in 2011 with the most striking turnaround coming in the resource-rich province of Saskatchewan, whose population grew by 6.7 percent. Saskatchewan had seen its population decline 1.1 percent in each of the previous five-year periods.

Saskatchewan had experienced a drain of people from the farms and small towns but is now resurgent because of a resource boom. Neighboring Alberta, rich in oil, had the fastest growth rate at 10.8 percent.

Politically of note is the fact that the four western provinces, where the ruling Conservative Party is strongest, has now surpassed the combination of Quebec and the four Atlantic provinces. In recognition of this growth, Parliament has added new seats in the West and in Ontario.

Toronto remained the country’s largest city with the metropolitan area, a magnet for immigrants, seeing its population rise by 9.2 percent to 5.6 million people.