Image via CrunchBase You know what sort of fell off in the second half of 2009? Twitter stories. It seemed like once the mass adoption phase of the microblogging service in the first half of the year quieted down, Twitter use plateaued in the second half of the year, giving us a fairly good idea of what the service’s reach would ultimately be. In social networking news, Facebook’s steady growth overtook Twitter’s headlines, and while Twitter remained one of the year’s top stories, it appeared to hit its peak. Which was kind of disappointing as its competitor continued to pass milestone after milestone . Twitter usage is notoriously difficult to put into metrics; unlike Facebook, much Twitter activity occurs on third-party apps that make up the rich Twitter ecosystem.

Twitter reached the one-billion monthly tweets milestone in December, according to Twello lead developer Matther Daines and reported in WebProNews.

According to Daines’ figures, there were 1.2 billion tweets in December, a significant jump from November’s 89 million. Twitter also passed the 100 million user mark last month.

The number of tweets per user also jumped 21 percent in December. Registered Twitter users tweeted an average of 11.5 times last month, the highest average since July, which probably means that people tweet more while on vacation.

The amount of tweets per user rose in a pretty fascinating way in 2009. In January of last year, only 3.9 tweets were sent per registered user. The number of tweets grew throughout the year as Twitter became more central to communications and to lives: by August it had settled into an average of 8.7 tweets per registered user, a level that grew to 9.5 in November.

So for many people, it was a question of figuring out how to use the service

Overall, the amount of tweets per user grew 1,514 percent in 2009.

(Via: WebProNews)

By Mark Alvarez