LinkedIn is the most popular social media site for posting jobs, according to survey results released today by Bullhorn Inc., a Boston-based software-as-a-service provider for recruitment.

Seventy-seven percent of job openings are shared on LinkedIn, followed by Twitter at 54 percent. Facebook came in third with 25 percent.

The report also found that 21 percent of jobs are posted to all three social networks and that the same percentage of jobs are not posted to social media sites at all.

The Northeast, specifically Maine and New Hampshire, is the most active region in social recruiting, while the Midwest, including Montana, is the least socially active.

Bullhorn’s survey pulled from the company’s user network of more than 77,500 recruiters.