I want to know the answer to the following question:
What is the name of the college a capella event that's been held since 1975?
All the background I'm provided with is that "Groups often join one another in on-campus concerts, such as the Georgetown Chimes' Cherry Tree Massacre, a 3-weekend a cappella festival held each February since 1975, where over a hundred collegiate groups have appeared, as well as International Quartet Champions". Is that enough to answer the question?