I think that's how a lot of the "special interest" orgs work, actually. I know there is a huge misconception that Delta Omicron is only open to music majors or minors, but that is not true. You only are asked to have an interest in the furtherment of music and musicianship. We don't have any percentages, though... I know in my collegiate chapter we only had a handful of actual music M/ms out of 30-40 girls.