CNBC NBC article Distractions 121 billion minutes per month on social media CNBC NBC article NBC article NBC article NBC article July 2012 CNBC, 6.5 hours online 230 thousand years 230 thousand years 260,060 years NBC article NBC article CNBC http://www.cnbc.com/id/100275798 CNBC NBC article http://www.cnbc.com/id/100275798 NBC article NBC article NBC article NBC article