Penguin 2.0 affected 2.3% of all English-US queries. Lest 2.3% sound to you like a smallish number, keep in mind that there are an estimated 5 billion Google searches per day. 2.3% of 5 billion is a lot. A single small business commerce site may depend on 250 different queries for substantial traffic and revenue. The impact is bigger than a little decimal number may suggest.