No, it wouldn't have been that high. I don't have exact numbers for the GBA in Canada, but I have posted a bunch of NPD Canada data in this thread
(Link)
As you can see, after factoring in the exchange rate, the Canadian market is about 6% of the US market. Obviously, the exchange rate fluctuates, and the companies don't always adjust the rate accordingly, so the number of units will vary a bit from the 6% figure, and different platforms will be more or less successful relative to the US. For example, the GC outsold the XBox in Canada, which was a reversal of the sales in the US. Anyway, I do know that the GBA was pretty even with the PS2 in Canada, and those were by far the two biggest platforms for 2003 & 2004. There is no way that both the PS2 and GBA could be up anywhere close to 17% of the US market when the Canadian market as a whole roughly 6-7% the size of the US market. For a quick and dirty comparison, PS2+GC+Xbox sold 12.7 million units in the US in 2003. Those systems sold 876,000 units in Canada in 2003. That's 6.9% of the US market for console hardware in 2003. That percentage stays pretty constant from year-to-year if you go through the data.
Anyway, if you go through the data, you can get some pretty good estimates of what each platform sold, based upon knowing the selling price for each system in Canada, mixed in with the other data (dollar revenues, order of sales for each platform, along with actual systems sold for Q4 2003. (By the way, GBA sold 208,000 units from Oct-Dec 2003 - you can compare that with its US sales for that period). Anyway, I may sit down one day to try to figure out those estimates for each system, if I ever find the time.
Just for anyone who's interested:
Hardware Launch Numbers:
DS - 28,000 units (Nov 2004) - 5.9% of US launch
PSP - 31,500 units (Mar 2005) - 5.1% of US launch
X360 - 32,100 units (Nov 2005) - 9.8% of US launch
DSL - ~15,000 units (first 2 days of launch) - 11% of US launch
It is worth noting here that the DS and PSP both had fairly typical launches relative to their US performance, but that the X360 and DSL both had very strong launches in Canada relative to their performance in the US.
I should also note that I had a report (which I have since lost) which gave revenue figures for the X360 for Dec 2005. If I assume that the core/premium ratio is the same as Nov 2005, then I believe that the total X360 sales through the end of Dec 2005 were about 58,000. However, I am just going by memory for that number, so take it with a grain of salt.