search engine ratings

this chart is from relevantknowledge, who uses software to monitor a panel of  web surfers, a sample of about 6,000 people. it analyzes the data to provide audience projections and demographics to its subscribers.

monthly comparison

below, the current estimate of how each search site compares against each other.

science magazine's bigger web

science also estimated that the web actually contains 320 million documents.  that larger universe of documents means that it found the search engines covered less of the web.  here is the percentage covered, using the science estimates for web size and index size: