iCrossing just released a study analyzing natural search results for non-branded keywords and found that more than 95% of all site traffic from search engines comes from page-one results. Healthcare, a deep-dive research topic, indexed slightly lower at 93% indicating searches seeking healthcare topics were some what more willing to dig deeper into their search results.
Bottom line, if you aren’t on page one of a SERP (search engine results page), than you aren’t getting the lion’s share of the traffic. It’s important to note that users expectations to “find” information seems to be getting higher. Prior studies indicated as low as 80% of clicks coming from page one.