According to pageviews data, pt.wikipedia main page has been loosing readers in a very very predictable way, in wich over the last year almost half of his pageviews was lost. Some monts ago the page was reformed, but still the values keep falling. This behavior seems inconsisntent with other projects main page, and even with global pt.wp siteviews, who keep stable. 
Any idea on what's happening? Is it possible to check referals to see where does people comes from, and where is the source of viewers lost?
 - https://tools.wmflabs.org/pageviews/?project=pt.wikipedia.org&platform=all-access&agent=user&start=2015-07-01&end=2016-07-22&pages=Wikip%C3%A9dia:P%C3%A1gina_principal
 - https://tools.wmflabs.org/siteviews/?platform=all-access&source=pageviews&agent=user&start=2015-07-03&end=2016-07-22&sites=fr.wikipedia.org|de.wikipedia.org|pt.wikipedia.org