Jaan,

the curve is cumulative and shows the percentage of traffic accounted for by rankings 1-10, 1-20, 1-30 etc along the X axis.

For example rankings 1-20 account for 90% of all traffic. The data was assembled from the analytics of about 10 sites. The curve climbs at a slower gradient than that demonstrated by the notorious "lost" AOL data.

I account for the variance on the basis that 1. My data is more biased towards b2b. B2b searchers may be inclined to look further into the SERPs. 2. AOL has a larger "sponsored" section than Google, Yahoo and MSN.

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