Listening to streaming audio is experiencing its largest year-over-year increase since Arbitron and Edison Research began tracking it in 1998. Weekly usage of internet radio — both the online streams of terrestrial broadcasters and streams from pureplay streamers such as Pandora — has increased from 22% of Americans 12+ in 2011 to 29% in 2012. That’s up from 12% in 2006 and 5% in 2001, reports Inside Radio.