Pandora is now essentially a mobile company. Although its users listen on multiple platforms, mobile is the driver of the company's growth and revenue. It's iPhone app arguably saved the company from going under in 2008.
Last week Pandora released revenue numbers for Q2. The company had earnings of $162 million. Ad revenue was $128 million and subscription and "other" revenue was more than $33 million.
The company also said that $116 million of that revenue was attributable to mobile. That works out to almost 72% of overall ($162 million) quarterly revenue coming from mobile devices. By comparison Facebook said that 41% of its Q2 2013 revenue came from mobile.
The company didn't break out mobile revenue in more detail so it's not clear whether the $116 million is all advertising or whether some of the subscription and "other" revenue is being attributed to mobile. My guess is that subscription revenue would not attributed to mobile.
Potentially then if the $116 is all ad revenue it would mean that essentially 90% of Pandora's ad revenue was being generated by mobile users.