A good while back, I ran across some quoted stats about this very thing. And today, I ran across an even more thorough discussion at Lilengine.com so let me share it with you.

But first, let me point out that the study was some years ago and it dealt with AOL search data. But I’ve not seen any similar study done for Google or any other search engine, so that makes this information the best and latest data that I am aware of – and I see no reason why it would not be relevant to Google, Yahoo, Bing, etc since this seems to be about human behavior, not the particularities of one search engine over another.

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“In 2006, some AOL search engine ranking data was leaked, and SEO researchers pounced. The analysis showed that the number one position brings with it a 47% average click through rate. Positions two, three, and four have click through rates of 13%, 9%, and 7%. Clearly, bringing your ranking up from third or fourth to first makes an enormous difference in a site’s traffic and its bottom line if it is a commercial site.

Of course, these figures are only approximations, but they do seem to hold water. People notice great differences between their statistics between the top rankings. Anecdotal evidence suggests that going from the #2 to the #1 spot can increase traffic by 100% or better. Dropping from #1 to #2 corresponds to a 30% to 50% drop in search volume.

As you move downward through the first SERP, the rate of decline of click throughs falls, and one interesting quirk that could be an artifact is that the number 10 position gets a slightly higher rate of click throughs than the number 9 position. Some speculate that users will be more likely to glance at the last listing while scrolling down to suggest searches or page navigation buttons. Once you move off the first SERP you’re close to being invisible.”

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[source]

In case you’re not familiar with the abbreviation, SERP = search engine results page.

Highlighting is mine.

- Gary Harvey, PageOneWithGary.com