About two years ago, ratings company Arbitron released a study of satellite radio ratings showing that Sirius and XM had about 17 million listeners. They’ve just released another study claiming the number has more than doubled, to over 35 million listeners. That’s great news for our friends at SiriusXM, but the study contains even better news when looking at the demographics and listening habits of their audience.

The respondents said that they spend 64% of their time listening to SiriusXM, as compared to 16% for AM/FM radio, 10% via mobile devices and 4% via streaming Internet. 71% listen in their cars. Also, they’re richer and more educated than terrestrial listeners, too. 56% of SiriusXM listeners are college graduates, as opposed to 24% for AM/FM listeners and 25% of the general population. Also, 24% of their listeners have household incomes of $150,000 or more, as compared to 9% of AM/FM listeners and 9% of the general population.

While it stands to reason that people willing to pay for satellite radio might be a little richer than those that don’t, but this is still a pretty enlightening survey. There haven’t been specific studies for the Liquid Metal channel, but it’s still pretty exciting to know that 35 million people could be listening to it, and even if just a fraction tune into the metal channel, it’s still one of the biggest potential audiences for metal 24/7.