Arbitron Inc. announced today that the index of total time spent listening to a spectrum of online radio stations measured by Arbitron’s MeasureCast Ratings grew 172% since January. During the week of November 4, Clear Channel Worldwide was the top ranked Web radio network with 1,516,061 hours of Total Time Spent Listening (TTSL). TTSL, also called Aggregate Tuning Hours (ATH), is the sum total of hours tuned by listeners to a given station or network. MUSICMATCH, Inc. was ranked number two with 1,201,343 hours of tuning. JazzFM moved into the top spot among individual stations with 363,038 hours of listening. Virgin Radio ranked number two with 312,073 hours of TTSL. The peak listening day was Wednesday, Nov 6, with 18% of the week’s online listening. 79% of weekly on-line listening took place between 5 a.m. and 5 p.m. Pacific time. 12% of the week’s total listening took place during the weekend. 86% of the measured listeners were between the ages of 18 and 54. 71% of listeners were men; 29% were women. In the U.S., 32% of listeners resided in the South; 29% in the West, 20% in the Northeast, and 18% in the Midwest.