From the media press kits, they have the following information about counterfeits notes in Canada (according to the RCMP).
[spreadsheet]Counterfeits° 2000° 2001° 2002
$5 °4,673°5,306°14,783
$10 °28,968°40,791°108,969
$20 °23,674°30,893°55,102
$50 °18,274°5,275°7,295
$100 °18,544°46,649°22,308
Total°94,133°128,860°208,457
[/spreadsheet]
coinsplus posted those numbers in the general forum.
Since the introduction of the new $10 (2000), the amount of counterfeit $10 found in circulation triple by 2002. If the new bills ($20, $50 and $100) have more advance security feature that are very hard (impossible) to copy than it's safe to assume that the number of fake $10 will continue to increase. I think that the BoC needs to add those new feature to the $5 and $10 from the journey serie.