OTTAWA - Senior citizens now represent 12.7 per cent of the population of the metropolitan area of Toronto, a ratio lower than the national average, the latest census numbers from Statistics Canada show.

Newly released census information on age and sex makes it clear that Canadian society is getting older. The data released Tuesday comes from census forms filled out May 10, 2011 - a moment in time when the first of the baby boom generation was turning 65.

The census showed that 706,665 people in what's known as the census metropolitan area of Toronto were aged 65 or older. The ratio of 12.7 per cent of the population compares to a national average of 14.8 and a provincial average of 14.6 per cent.

Five years ago, the 2006 census showed that 11.9 per cent of the metropolitan population of Toronto were seniors.

Statistics Canada uses the term census metropolitan area to describe any area with a population of at least 100,000, where the urban core of that area has at least 50,000 people. Looking at metropolitan areas this way takes in to account the growing impact of suburban areas on Canada's largest cities.

Despite the growing number of seniors in Canada, the country remains one of the youngest in the industrialized world. Among G8 countries, only the United States and Russia have a lower percentage of citizens aged 65 and over.

Still, an aging population presents challenges - especially because Canadians are not having as many children as previous generations. By the time the next census is taken in 2016, Statistics Canada projects the country will be home to as many senior citizens as children. That will present governments with difficult choices such as how much funding should be allocated for health care versus education.

The number of children in the metropolitan region of Toronto - those aged 14 and under - has increased since the last census.

The new data shows that children make up 17.5 per cent of the population. Across Canada, children represent 16.8 per cent of the population and the provincial average is 17 per cent.

Those of working-age population in the Toronto region - people aged 15-64 - represent 69.9 per cent of the area's residents. That's up from the 2006 census when 69.5 per cent of the population was made up of working-age residents.

The median age of the metropolitan Toronto area was 38.6 years, compared with 37.5 years in 2006.

Nationally, the median age in 2011 was 40.6 years and the provincial median age was 40.4 years.

Statistics Canada defines median age as the point where exactly one half of the population is older than the median age and the other half is younger.

The national census is conducted every five years. The information published Tuesday is the second of several releases of data to come from Statistics Canada over the next year and longer that will eventually paint a detailed picture of the country, right down to the local level - including age breakdowns of the population, family makeup, languages spoken, immigration and ethnic origin, the level of education attained and income earned.