the ratio would be arb real quick in the old days with a no risk trade both side of the boarder at the same time .... you will see it intra day from time to time... but you have to have institutional status to play... your currency swap would kill you with out the size.. this process also keeps the mkt inline..

just one point the US nyse price of cnq is the one to react to a change in the Canadian dollar.. as trade mention the opposite.. so if the canadian drops to .50 US cnq would be 15 US and the tse 30.. other factors would change the canadian price like crude oil at 30 hence low canadian and cnq at 20 and 10 us.. ect...