New Normalized Listening Metric (for varying track lengths)

I wanted to suggest a new metric option that could better reflect listening habits, especially for users like me who listen to different genres, with either very long or very short tracks.

Currently, using minutes listened over represents genres such as classical music, while stream count favors shorter tracks, which creates an imbalance in the top lists.

My suggestion: a new normalized metric based on estimated "equivalent full listens," calculated e.g. as: equivalent_listens = minutes_listened / track_duration (this should work for track sorting, but no clue if it requires too much processing for genre or artist)

Thank you for the amazing work on Spotistats!