New figures from comScore, which measure digital use, show that Facebook, LinkedIn, Twitter and Tumblr “reached new heights” in the US in May.

comScore’s blog on the “network effect” shows social networking accounts for almost 14 per cent of the time people spend online – or one in every six minutes.

The new stats show social blogging site Tumblr has grown by 166 per cent in the past year, reaching 10.7 million visitors in May, its first month surpassing the 10 million visitor mark.

A post states:

Today Facebook is the fourth largest US web property in audience size with 157.2 million visitors in May, representing its all-time high and a gain of 3.2 million visitors vs. the previous month. While other reports have been circulating that Facebook witnessed a pronounced user decline this month, comScore data shows quite a different story. Given that Facebook now reaches 73 per cent of the total US internet population each month, one thing we should anticipate is that the site’s audience cannot grow forever. The law of large numbers says that once a site has penetrated the majority of a market, each incremental user becomes that much more difficult to attract. So given its size, Facebook’s future US growth is likely to come more from increasing usage per visitor than its ability to attract new users in perpetuity. One impressive stat to note is that Facebook’s average US visitor engagement has grown from 4.6 hours to 6.3 hours per month over the past year, so it appears to be succeeding in that regard.

The author states:

Upon the release of comScore’s May US data, I immediately noticed that it was not just a banner month for Facebook but also for several other leading players in the social networking category who also reached all-time US audience highs: Linkedin (33.4 million visitors), Twitter (27.0 million) and Tumblr (10.7 million).

Twitter also had a particularly strong month in May with 27 million US visitors, representing an increase of 13 percent in the past year. (Note: while much of Twitter’s usage occurs away from the Twitter.com site, past comScore research has indicated that approximately 85-90 per cent of Twitter users visit the website each month). Twitter’s success in May can likely be attributed in part to the exceptionally buzzworthy news story of Osama Bin Laden’s death, as well as ongoing discussion of the Royal Wedding.

The full post is at this link