Think you're the only one "poking" grandma on Facebook? Think again. A new Pew Center study released Friday shows that 65 percent of adults now use social networking sites like Myspace, LinkedIn, Facebook and Twitter - up from 61 percent just a year ago, and more than double the 29 percent surveyed in 2008. Compare this to the numbers when the question was first posed in 2005, when only 5 percent of adults (and 8 percent of all users) said they used social networking sites. The most growth, according to the study, was primarily among "boomers" aged 50 to 64, whose usage levels have spiked by 60 percent in the past year — from 20 percent to 32 percent.