According to TorrentFreak.com, Google has removed over 50 million URLs from the search results in 2012. It was expected that the number would rise due to Google’s Pirate update in August 2012, which involves the removal of sites that have a large number of legitimate DMCA takedown requests filed against them. The most “takedown” requests came from the RIAA (Recording Industry Association of America). Check out the graph below that shows the dramatic increase in takedown requests that starts in August when the Pirate update was introduced.
Numbers are expected to keep rising in 2013. Unfamiliar with the Pirate Policy? Read this article from Search Engine Land that covers the update.