William has seen 13 bands.

Band Concerts Seen
  Grateful Dead 5 concerts
  New Riders of the Purple Sage 3 concerts
  Yes 3 concerts
  Crosby, Stills, Nash & Young 1 concert
  Deep Purple 1 concert
  Focus 1 concert
  Free 1 concert
  John Martin 1 concert
  Poco 1 concert
  Ten Years After 1 concert
  Traffic 1 concert
  Wild Turkey 1 concert
  ZZ Top 1 concert