What you don't see on Amazon is the buying habits of people outside the USA.
As opposed to the dpreview 'data' you provided, which doesn't show anyone buying anything anywhere.
No, it shows what cameras people are interested in. People are no longer as interested in looking at or reading about Canon cameras as they used to be.
Interested in in a five day span of time. Canon hasn't released anything in the last five days...so why would they be in that DPR list? When Canon releases something, especially something big, people will show interest.
In the past, Canon was always well represented in the top 10 regardless of how recent the announcements were.
You would need to back that up with actual data, because that is not what I remember.
I would also point out that currently, and for the last several days, the top four cameras on that list were all released recently, within the last few months. The average distribution of the rest is 2.3%. An average of 2.3% of searches are made for the top items on the list that are not very recently new cameras. Of ALL the cameras in the world, fully three are still Canon, and all were released some time ago. No matter how you slice it, Canon still has the majority representation on the DPR list. As they always have. Imagine how that list will look when Canon releases the 7D II. Imagine how it will look when the rumors about the 7D II start to get more solid. That major representation of 3/10 will jump...to 4/10, 5/10. When a major new camera from Canon hits the shelves, and people exit "waiting mode" and start evaluating which Canon camera to buy again, I'd bet Canon once again takes over the majority of that list...until the fervor dies out and people finish making their decisions. Then, well, then once again the list will be dominated by the most recent releases, from whatever brand is releasing.