Yes, all the time. There is no way in heck I'd be in a car and not wear it.
Seatbelt use by all vehicle occupants became mandatory in British Columbia pretty much when I was born, and I think BC has the highest seatbelt compliance rate in Canada.
I presume in neighboring Washington state, seatbelt use must have been a problem, because the Washington DOT has erected signs along all the freeways telling you to "Click it or ticket! - Minimum $86 fine." What I found interesting is, on a AAA Triptik map I have, it says that seatbelt use is mandatory in all states except New Hampshire. I think that is just plain stupid that NH does not have a seatbelt law.
As they said in those TV commercials in the early 80's... "you could learn a lot from a dummy. Buckle your safety belt."
Daniel