(Tumblr) are growing by a quarter billion impressions every week”… Last week Tumblr did 1.2 billion impressions, or pageviews, and it is adding 250 million every week. Just think about that for a second. Over the last 30 days, that came to 4.2 billion pageviews.
…. All of that is coming from 19 million unique visitors per month globally, according to comScore"