New Stat (Average Duration Streamed)

There should be a stat that shows the average number of minutes streamed for

each song (i.e. minutes streamed divided by number of streams).

Additionally this ratio could be divided by the total duration of the song to indicate what percentage of the song the user listens to on average. For example, a 0.9 indicates that on average the user listens to 90% of the song, whereas a 0.2 indicates that on average the user only listens to 20% of the song.