The research shows that millennials have a dominant role on many of the top social media sites, representing 70% of Instagram users and 61% on Twitter.

The median ages of other social site users are 44 for LinkedIn, 42 for Google+, 38 for Pinterest, 38 for YouTube and 32 for Twitter.

It found that LinkedIn had the highest median household income (approximately $112,500 ) and the highest education levels among the top social media, photo, or video-sharing sites.

Across the seven major social and photo/video sharing sites, men outnumber women among users in just three: LinkedIn ( 55% of users versus 45%), Twitter ( 54% to 46%) and YouTube ( 51% to 49%). Women are the majority of users of Facebook ( 57% versus 43%), Google+ ( 53% to 47%), Instagram ( 60% to 40%) and Pinterest ( 81% to 19%).

Florian Kahlert, managing director of GfK MRI, said: “These results show that many of the social media applications are becoming mainstream, which bodes well for the long term viability of those companies. At the same time, this growing acceptance raises the bar for media planners (and inventory sellers), because just adding social media sites to a plan without other sophisticated targeting no longer automatically increases your younger or savvy target groups.”

GfK MRI’s Survey of the American Consumer is a single-source database derived from continuous surveys of approximately 25,000 US adults annually.