"Barracuda Labs, a security company that says it has surveyed 19 million Twitter accounts, reports that 73 percent of Twitter users have tweeted 10 or fewer times. And 34 percent of users have never tweeted at all.
That’s a lot of quiet users, but it’s less than before: Barracuda says those numbers are down from 79 percent and 37.1 percent, respectively, in June of last year."