A new Jupiter Research study finds that awareness of digital music is driven by MP3 devices like the Apple iPod. As devices become more popular, more people are ripping their CDs into digital format and transferring them to their devices, the group says.

According to the study the average size of digital music collections have increased over the past three years, with 18% of them now over 1,000 tracks. These collections are primarily built through ripping music from CDs. More than 60% of MP3 device owners regularly rip music to their device.

In addition, more users are subsequently building playlists out of them as well, with 58% of iPod users and 44% of other device owners doing so.