The Average iTunes music library..
The AVERAGE NUMBER OF SONGS in an average customer’s iTunes library is 7,160. The average number of songs missing album artwork is 4,230. The average number of songs in an iTunes library missing the name of the artist is 490. The average number of songs missing track or year information is 1,984. The average number of **duplicate songs is 814.
Source: TidySongs, a popular iTunes organization application, has taken a look at around one million iTunes libraries over the last two years and has reported their findings.