Some observations
Generations alternate between innovation and conservation.
In lean times, artists arise from the bluegrass heartland (NC, VA, TN, KY, WV).
Interest in bluegrass occurs in adolescence, followed by a 10-12 year apprenticeship, and a median recording career from ages 25 to 53.
Long careers ìcrowd the marketî as generations overlap.
There is not one African-American or Hispanic in the database.