A University of Hertfordshire has found the iPod of the average UK teen or student has 842 illegal tracks. The average number of songs on each digital music player is 1,770, meaning each player has 52% legally acquired songs. The proportion of illegally downloaded tracks for youths aged 14 to 17 is 61%. No breakdown was given for songs ripped from purchased CDs versus those acquired from digital stores or ripped from copied CDs.

In 2006, Jupiter had found the average iPod had 5% of its songs acquired from iTunes. If a similar figure holds for UK youths, that would put the number of paid downloads per iPod at about 88. The remainder, 832 songs, would be ripped from purchased CDs.

In addition, the study found 96% of 18 to 24-year-olds surveyed engage in some sort of illegal copying, and nearly two-thirds copy CDs for friends and share songs via email.

The numbers will probably surprise many people, and they're sure to add to the common opinion that piracy is public enemy #1. That may or may not be true. Piracy could be in the top three or four reasons for the decline in recorded music sales. There are certainly other factors that need to be addressed: format substitution, games, broad technology changes, the decline of music retail and a general distrust of the music industry.

Update: You can download a PDF (1.57MB) of the study here.