The internet radio service known as Pandora has just hit a pretty significant milestone by reaching 200 million registered users in the United States and 1.5 billion hours of streamed music in March. Pandora first began in 2005 and by 2011, 100 million users had signed up. The next million only took less than 2 years to reach. Currently 67 million users are considered monthly active listeners.
Congratulations Pandora.