The Incredible Shrinking Oregon Bach Festival MUSIC Posted: June 15, 2017 2:31 pmDuring the transition from Helmut Rilling to Matthew Halls, OBF attendance dropped by over 50 percent : 2011 had 44,148; 2014 had approximately 20,000. There are no figures for recent years. Click to share on Facebook (Opens in new window)Click to share on Twitter (Opens in new window)Click to email a link to a friend (Opens in new window)