Then: LinkedIn has over 50m members worldwide. 
Now: Officially, Linkedin has grown 100%, now having over 100m professionals who use the platform worldwide. 

Then: Facebook has 350 million active users on global basis.
Now: Facebook officially hit the half-billion member mark last year. According to figures from Socialbakers, there are now some 640m Facebook users worldwide.

Then: 50% of active users log into Facebook each day. This means at least 175m users every 24 hours.
Now: Still citing the 50% active rate, using the official 500m figure, this means at least 250m users every 24 hours. This is more than a 40% increase in 12 months.

Then: Flickr hosts more than 4bn images.
Now: Flickr continues to grow at a steady rate, having increased by some 25% in the last twelve months. At the end of 2010, it was hosting more than 5bn images.

Then: Wikipedia has 14m articles and 85,000 contributors.
Now: Wikipedia now has more 17m articles. The site now has an army of 91,000 active contributors.

Then: 65m users access Facebook through mobile-based devices.
Now: It may well be the year of mobile... For Facebook. Users accessing the site through mobile devices now tops 200m - an enormous 200% increase in around a twelve-month period.

Then: There are more than 3.5bn pieces of content (web links, news stories, blog posts, etc.) shared each week on Facebook.
Now: Clearly, Facebook is still growing: More than 30bn pieces of content is shared each month, which is an average of 7bn pieces a week.

Then: There are 11m LinkedIn users across Europe.
Now: Go Europe! There are now 20m+ EU Linkedin members.

Then: The average number of tweets per day was over 27m.
Now: Twitter now states that 95m tweets are written each day. This is a staggering 250% increase.

(c) econsultancy