Website traffic: Search vs Share

I was just reading this Seeking Alpha article about Facebook and saw the attached image, where for a while “link sharing” on sites like Twitter, Facebook, and Pinterest overtook search engines in terms of “share of website visits,” but in 2017 search engines once again overtook sharing. The question is, does this mean that fewer people are using those social websites, or fewer people are sharing and clicking on those links?

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Website traffic: Search vs Share