One funny answer to it I got from my colleague Dilip Rao is, "Employees of respective search engine companies" :-). And probably that is also they are using because Google is banned there. He he ..
I was seeing market share for search engines here. It shows 80% market share is with Google. Rest 20% is distributed among other search engines in which Yahoo! has 12% of market share. After reading this statistics I started wondering. Because, all the people whom I know personally and professionally uses Google. All persons who are close to me is conditioned in positive way by me to use Google. In other countries also most of the person related to my work uses Google. Than who is this 20% of people?