Google Ads' Influence Organic Click-Through Rates [CHART]
On average, the presence of ads on a search results page caused the organic CTR of the first position to drop by 30% — from 25.7% organic CTR in the absence of ads to 17.9% CTR when ads are displayed.
So, if you were counting on a 30% or more CTR for a top ranking in your performance calculations, think again. With most search queries displaying ads, the odds are that the real CTR you will have is much lower. Read the rest at Search Engine Land.