[AJ007]

I think the answer lies in several areas, yours probably explains 90% of it.

Other things:

-Comparison of average number of visits a month per unique user: Google-21.5, Yahoo-18, Bing-8.9

-From what I have seen with my companies own internal numbers, Yahoo & Bing users may be more inclined to click on search ads. Unless a webmaster is running a big ad campaign, they aren't going to see huge volume from these two search engines.

-What percentage of Yahoo's 140m monthly users are visiting the site to use Yahoo Mail verse to search?

I recommend using compete.com for traffic intelligence. It fairly accurately reflects my own site's data. I've been paying $500 a month for their lower premium tier for a good 2 years with no complaints for anything other than idiotic salespeople.

Another comment, as a webmaster comparing your percentage of traffic from one search engine verse the other is meaningless unless your rankings are exactly the same in all of them. A real test would have to be done with a PPC campaign strictly receiving traffic from google.com, bing.com, and yahoo.com