http://en.wikipedia.org/wiki/Canadian_coinage#History
Canadian dimes, quarters, halves, and dollars were 80% silver during 1920-1967.
In 1967, they began a gradual debasement to phase out silver. At some point in 1967, a composition change was made from 80% silver to 50% silver, so a '67 coin could be either type. I do not know a good way to tell them apart.
They did another composition change again in 1968, this time from 50% silver to 99% nickel, so again a coin from that either could be either metal. They're easy to sort... the non-silver coins are magnetic, the silver coins are not.
I do not know if Canada has ever made silver proofs. To my knowledge, Canadian nickels have never contained silver, at least not since World War I.
