[Analytics] Drop in mainpage pageviews?

Hi, Starting from an unrelated discussion on meta, I noticed a significant drop in main page views for several wikis starting from April this year. Is there anything we (or Google) did at that time to justify this drop? ro.wiki: http://tools.wmflabs.org/pageviews/?project=ro.wikipedia.org&platform=a… hu.wiki: http://tools.wmflabs.org/pageviews/?project=hu.wikipedia.org&platform=a… fr.wiki: http://tools.wmflabs.org/pageviews/?project=fr.wikipedia.org&platform=a… de.wiki: http://tools.wmflabs.org/pageviews/?project=de.wikipedia.org&platform=a… en.wiki: http://tools.wmflabs.org/pageviews/?project=en.wikipedia.org&platform=a… (slightly different pattern) The same cannot be said for other projects, for instance uk.wiki: http://tools.wmflabs.org/pageviews/?project=uk.wikipedia.org&platform=a… Thanks, Strainu