Last week Pew Internet released new data that showed who is using Twitter and other social media sites, with Twitter now enjoying an 18 percent penetration rate amongst internet users in the U.S., up from just 8 percent in 2010.

Perhaps most pleasing for Twitter was that the numbers also revealed that usage amongst all age demographics is also growing, with the 18-29, 30-49 and 50-64 age zones more than doubling in this same period.

Users aged 65 or over have also seen growth of one percentage point, representing 5 percent of all 65+ year-old internet users in the United States.

(Source: eMarketer.)