High school students aged 13 - 18. I was surprised by the number, but the findings are in line with several other studies.
At least three separate studies that I've seen concluded that 12% - 14% of Canadian high school students
admit to being LGBT. I'll try to dig up the links to them as a reference. The surveys were done at random schools by handing out questionnaires to all the students in the class. I have yet to see any that have come up with conflicting conclusions.
It's also in line with a study
commissioned by the National Post that showed that the younger you are, the more likely you are to identify as LGBT. Only 2% of people 65+ identified as LGBT; this gradually increased to 10% as you got to 20 year old age group. Makes sense that the next youngest age group would be in the 12% - 15% area.
And remember, these numbers only represent people who've admitted to being LGBT. I think it's fair to conclude that there are quite a few who lied given the homophobia that still exists.