I have a researcher who is looking for cross-sectional data over time that deals with sexual history of youths/adults in Canada. He has looked at both the Canadian Health Survey and the Canadian Community Health Survey which does deal with these questions but doesn't go far enough back. I've also looked at the National Population Health Survey.
Another lead is the BC Adolescent Health Survey <http://www.mcs.bc.ca/>, but any other suggestions would be most appreciated.
In addition to the ones your researcher has found, the Health Promotion Survey, 1990 asks these questions and you may also find additional information for college age people in the survey of Male-Female Dating Relationships in Canadian Universities and Colleges. Some Gallup opinion polls also seem to cover this as well. You'd think some cycles of the GSS cover this too?
I searched "intercourse" in <odesi> at the variable level:<http://odesi.ca/search/search.html?q=intercourse&field=VL&coll=odesiall&coll=DLI&coll=DLI_aggregate&coll=CGP&coll=CAD&date-gt=1871&date-lt=2015#10>.
There may also be data in ICPSR that covers this with a Canadian sample...