Professional social network LinkedIn has passed 500m registered users, an increase of around 66m over the past year.

Those users span 200 countries and 9m companies – but its worth noting that the membership figure doesnt necessarily reflect the active userbase.

Previous reports from LinkedIn suggest that about a quarter of members return on a monthly basis, which would put its MAUs around the 125m mark. By comparison, Facebook has 1.9bn MAUs, and Twitter 313m.

LinkedIn was acquired by Microsoft last June for a price of $26.2bn (£20.5bn), essentially putting a $52-a-head cost on each of its users. Its worth noting that, unlike its competitors, LinkedIn has a way of directly making money from each user through its subscription service, which makes it the highest-grossing social app on the App Store, according to Apptopia.

LinkedIn also revealed the regions and verticals where users have the most connections. London is the worlds most connected city, with Londoners averaging 307 connections on the service, but the United Arab Emirates is the most connected country,  with an average of 211. Unsurprisingly, the most connected industry and job function are recruitment, averaging 702, and HR, at 415.