Twitter Hits 75 Million Users, Most Of Them Inactive

CLICKZ — Twitter continues to sign up users at a remarkable rate, though a vast majority of those users almost never use the service, according to a new study from RJMetrics. The online measurement firm, which is based in Camden, N.J, analyzed Twitter's backend data for a closer look at the numbers behind the nearly three-year old social platform. What they found was that Twitter has a remarkably high number of inactive accounts, but enjoys ever-deeper levels of engagement with its frequent users. Seventy-five million people signed up for a Twitter account by the end of 2009, the study said, though only 17 percent of them sent even a single Tweet in December, an all-time low for the micro-blogging service...