Google had an effective year with fines.
According to Google’s recent announcement, in 2015 they fined more than 4.3 million webpages manually. The number is surprisingly high, because with manual controls the sites have been combed through by human workers who decide about the fine, and then the webmaster gets a notification about it.
It requires a huge human capacity from the company. The announcement also says, that the number of review requests has jumped to 33%. If a website gets a manual punishment, they have a chance to correct their mistakes, and they can ask Google to remove the fine. It also requires human work.
The pages can get a penalty for several reasons. The most common is when their content is a copy from somewhere else, or when the texts are really hard to read. Also quite usual when a website buys some links to be among the first finds. The sites that became punished are further back in Google’s finds list, and get much less visitors daily.
Last year Google started to use a new algorithm in order to remove web-spams from the search. It is an automatic penalty, and it further back the pages in the search engine. Also the users helping Google to find the incorrect pages. Last year more than 400,000 accusations arrived at Google. Amongst them, 80% were really spam, and 65% received a fine too.