When a website is trendy, people search for it. Some people just want to find the website itself; other people are looking for background information about the website such as press articles. Because Google publish statistics about searches, we can get a clue how trendy a particular site is.
Facebook’s traffic was still growing at the time of their last annual report (which covered 2013). Interest in the site, though, has been falling since mid 2011. Does that mean that traffic will soon start heading downwards too? Will there be an unpleasant surprise in the 2014 annual report, once it is made available?