Pandora announced that on Tuesday it passed 200 million registered users for its online radio service. Although it took the company six years to sign its first 100 million users, from July 2005 to July 20011, it took a little less than two years thereafter to double that figure. In addition, 140 million out of the 200 million also access their accounts from mobile devices. Pandora firmly believes that it’s on the right side of radio innovation, for both artists and music fans; however only 70 million of the 200 million registered users use the service on a monthly basis. At the same time, this ratio is significantly more promising than that of Spotify, which boasts 24 million active users, only 6 million of which pay for the service.