Ok, this is a little weird.
First, go look at this page.
What’s weird in this data is the difference that you can see between the one-word and the two-word searches.
I was asked to look into this by someone at one of the Blog Search Engines (who shall remain anonymous), under the suspicion that there would be some difference in the performance of these these two-searches.
I want to watch this for a while before I publish the next Search Index results. What I am seeing here is that there could be a methodological issue in the search. Be interesting to see how these react to three word searches.
If any of the folks from the search engines want to chat about this, drop a comment in the usual place.