Your mainstream percentage!
Go through your top 10 artists and add up the total number of listeners. Divide the average by the number of Red Hot Chili Peppers fans (Red Hot Chili Peppers is - at the moment - the artist with the most listeners - Radiohead is second). That is your "mainstream percentage".
My Top Ten:
1.The Flaming Lips - 156,440
2.The Beatles - 309,171
3.Ryan Adams - 63,718
4.Acid Mothers Temple & The Melting Paraiso U.F.O. - 5,790
5.Can - 28,039
6.Laibach - 14,743
7.The Mars Volta - 112,434
8.…